Name: Date: Period: Spring Grove Area High School Chemistry I Chemistry I Honors Laboratory Manual Miss Frey Mr. Henning Mrs. Kimber Student Name:___________________________________________ Homeroom:______________Chemistry Period:________________ Chemistry Teacher:________________________________________ 1 Name: Date: Period: SPRING GROVE AREA SCHOOL DISTRICT SCIENCE DEPARTMENT SAFETY From: The High School Science Department To: All Science Students The laboratory is a safe place to experiment if you are careful and safety conscious. You must assume responsibility for the safety of yourself and your classmates. The following safety rules will guide you in protecting yourself and others from injury in the lab. In addition your instructor may have a list of additional rules which must be followed in the laboratory while under his/her supervision. When necessary, your instructor will also give you specific instructions for a particular laboratory exercise. 1. The laboratory is to be used for serious work. No inappropriate behavior of any type is permitted at any time. 2. Do not handle the equipment in the laboratory unless you have been authorized to, or you are performing an experiment, which makes use of that equipment. 3. Only experiments, which your instructor authorizes, are permitted. Always obtain your instructor’s permission if you would like to modify an experiment or perform an unassigned experiment. 4. Study your laboratory assignment prior to coming to class. If you are in doubt about any procedure, ask your lab instructor. 5. Use safety equipment provided for you. Know the location of available safety equipment, such as fire extinguishers, showers, etc. 6. Handle and use all instruments and equipment properly and with care so as not to injure yourself, others, or damage the equipment. 7. Report any accident, injury, or incorrect procedure to you instructor at once, when/if it occurs. 8. Handle toxic, combustible, or radioactive materials only under the direction of your instructor. 9. Never take any chemical substance or draw poisonous materials into a glass tube with your mouth. At no time should you have any foreign material in your mouth during the lab. 10. If you spill toxic, combustible, or radioactive materials notify your instructor at once. He/she will give you directions for cleaning up the spill. 11. Use gas, electrical, and water outlets properly. 12. Use electrical equipment only under the supervision of your instructor. 13. Students should be aware of loose clothing, long hair or other possible fire catches and appropriate corrections should be made. 14. Keep your work area orderly and clean at all times. When your investigation is complete, return all materials and apparatuses to their proper locations. 15. When your experiment is complete, clean up and dispose of materials properly. 16. Be sure to wash your hands after handling any toxic materials in the lab. WE HAVE READ, DISCUSSED, AND UNDERSTAND THE SAFETY REGULATIONS FOR THE SCIENCE CLASSROOM. Student’s Name (Printed): _________________________________________ Date:___________________ Parent’s/Guardian’s Signature: _________________________________________ Date:__________________ Student’s Signature: _________________________________________ Date:___________________ 2 Name: Date: Period: 3 Name: Date: Period: 4 Name: Date: Period: 5 Name: Date: Period: 6 Name: Date: Period: EVIDENCE OF CHEMICAL CHANGE Objectives: 1. Observe the types of evidence that indicate that a chemical change has taken place. 2. Infer from observation of a chemical change that a new substance has been formed. 3. Identify and record data that shows how heat is involved in a chemical change. 4. Explain why a substance can be either a reactant or a product in a chemical reaction and how this relates to recycling. Introduction: Substances may be created by a chemical change and may also undergo chemical change. If a substance is produced as a result of a chemical change or a reaction, it is called the product. If the substance is subject to a chemical change, it is the reactant. One way to indicate if a chemical change has occurred is to observe the properties of both the reactants and the products, since they will be different. In this experiment you will observe a series of reactions beginning with copper (II) nitrate. All of the reactions will take place in the same test tube, with the reactants becoming products and those products becoming the reactants for the next reaction. This chemical conversion is useful when we recycle materials. For instance, the copper (II) nitrate we are using in this experiment was created from a reaction between elemental copper and nitric acid. Through a series of reactions, we can recover the copper. Another example is with metals that are changed into alloys and shaped into soft-drink cans, and by recycling the cans the aluminum can be recovered. YOU MUST WEAR GOGGLES AND APRONS FOR THIS LABORATORY EXERCISE! Equipment: Materials: 1 large test tube Test tube rack 1 – 100mL beaker 10mL Graduated cylinder Beaker tongs Bunsen burner Stirring rod Ring stand Iron ring Wire gauze Forceps 1.0 M copper (II) nitrate, Cu(NO3)2 3.0 M sodium hydroxide, NaOH 3.0 M hydrochloric acid, HCl 8 cm piece of aluminum (Al) foil, rolled 7 Name: Date: Period: Procedure: 1. Place 100 mL of water into the 150 mL beaker and place on the wire gauze. 2. Heat the water to a boil to use in step 5. 3. Measure out 2mL of copper (II) nitrate and pour into the large test tube. 4. Measure out 2mL of sodium hydroxide and pour into the large test tube containing the copper (II) nitrate. 5. Mix the two solutions slowly with the stirring rod. You have now created two new products called copper (II) hydroxide and sodium nitrate. a. Record any observations. b. Touch the outside of the test tube. Is it warm or cold? 6. Remove the stirring rod and place the test tube in the water bath from step 1 & 2. Make sure the test tube is facing the wall and not out towards you or any partners. 7. Heat until no more changes occur. The new products are copper (II) oxide and water. a. Record any observations. 8. Remove the test tube from the water bath. Turn off the Bunsen burner and gas. Cool the test tube for two minutes in the test tube rack. 9. Place the test tube in a second beaker that contains cool or room temp water. Allow to cool an additional two minutes. 10. Remove the boiling water from the wire gauze and discard the water. 11. Once cool, remove the test tube from the water bath and place back in the test tube rack. 12. Measure out 4 mL of hydrochloric acid and pour into the large test tube containing the copper (II) oxide and water. 13. Mix the solutions slowly with the stirring rod. If the solution does not turn clear, add 2 more mL of hydrochloric acid and continue stirring until it clears. You have now created two new products called copper (II) chloride and water. a. Record any observations. 14. Place an 8 cm piece of aluminum foil into the test tube and leave it until no more reaction takes place. This may take a few minutes to occur. Two reactions are taking place: one will make copper and aluminum chloride, and the other will make hydrogen and aluminum chloride. a. Record any observations. b. Touch the outside of the test tube. Is it warm or cold? 15. Use the forceps to remove the aluminum foil/copper from the test tube. Compare it to a sample of copper you receive from your teacher. a. Record any observations. 16. Dispose of the aluminum foil/copper in the trash can and place the liquid contents that remain in the labeled beaker in the fume hood. 17. Clean up your lab station, putting away all materials where they belong. Clean the test tube with the soap solution before putting it away. 8 Name: Date: Period: Observations & Data: 5a. ________________________________________________________________________ 5b. ________________________________________________________________________ 7a. ________________________________________________________________________ 13a. ________________________________________________________________________ 14a. ________________________________________________________________________ 14b. ________________________________________________________________________ 15a. ________________________________________________________________________ Reactants Copper (II) nitrate + Data Table Observations of Precipitate Formed Products Observations of Supernate Formed + Sodium hydroxide Copper (II) hydroxide + + Heat Copper (II) oxide + + Hydrochloric acid Aluminum + + Copper (II) chloride Aluminum + + Hydrochloric acid 9 Name: Date: Period: Post Lab Questions: 1. What are some causes of chemical changes? 2. In what two ways is heat involved in a chemical change? Cite two specific instances from this experiment. 3. What is the color of the copper solutions in this experiment? 4. Which substances used or formed in the experiment are elements? 5. Which substances used or formed in the experiment are compounds? 6. List four types of observations that indicate that a chemical change has occurred. 7. Describe the advantages and disadvantages of recycling metals as was done in this experiment. 10 Name: Date: Period: Quantitative Analysis of an Ocean Water Sample Objective: To design and carry out the separation of a mixture. Background: After all of that oil spilled in the Gulf of Mexico, it’s finally hit the fan. Aquatic Life is altered: fish and shellfish are dying. The shrimp population in particular is vastly diminished, and BP is denying any responsibility for the population decrease. NOAA, the National Oceanic and Atmospheric Administration has contracted your company to conduct a quantitative analysis of the ocean water in the affected area. NOAA requires that you report the mass % of sodium chloride, sand, iron, and oil (in the form of tar balls) in your water sample. NOAA officials will then use your findings to decide if they have enough evidence to prosecute BP officials. Since you must conduct a quantitative analysis, you must separate the ocean water into its components, which include water, sodium chloride, iron, sand, and tar balls. You must then obtain the mass of each individual substance, and calculate the mass % of each in the mixture. Procedure: 1. Observe your ocean water sample. Using your observations, and your knowledge of each of these substances, make a list of the physical properties you could use to help you separate the components of this mixture. Then describe how you could separate these substances from the mixture. Substance Physical Properties Possible Separation Method Water Sodium Chloride Sand Iron Tar Balls 2. Next, make a flow chart of your separation process, and have your instructor initial it before you begin the physical separation. 11 Name: Date: Period: 3. Make a list of materials and lab equipment you will need to carry out the separation. If there is anything on your list that is not in your lab station, see your instructor. 4. Write the procedure you will carry out to separate the components. Use the correct names for materials and equipment. Use literate sentences and correct spelling and grammar. 12 Name: Date: Period: 5. Carry out your procedure and complete the data table below. substance Mass (g) sample % of sample ------ Oil (tar balls) salt sand Iron Water Results: Ocean Water Sample Number: _________________ % NaCl __________________________________ % Sand __________________________________ % Iron ____________________________________ % Tar Balls ________________________________ 13 Name: Date: Period: Scientific Method Purpose: To use the observations of chemical reactions to understand the stops of the scientific method. 1 – State the problem, 2 – State a hypothesis, 3 – Experiment, 4 – Collect data, 5 – Organize data, 6 – State a conclusion. Procedure: 1) Using pipets, that are labeled to indicate the solution, place 4 drops of the solution indicated into one of the wells on the microtiter plate. a. USE ONE DROP OF SOLTUION # 5. 2) To the same well you just used, add 4 drops of the second solution indicated. Carefully stir with a stirring rod to complete the reaction. 3) Record all observations! 4) If a third solution is listed, add 4 - 8 drops of that solution to the same well, to ensure a permanent change is evident after stirring. 5) Record all observations! 6) Use a new well, for each new mixing. 7) Clean microtiter plate thoroughly when finished. A) SAFETY GOGGLES AND APRONS MUST BE WORN!! B) ALL DATA IS PERTINENT TO THE SUCCESS OF THE LAB ~ BE SPECIFIC WITH ALL RECORDED OBSERVATIONS! Solutions: Names of compounds and chemical formulas are given Barium chloride Sulfuric acid Sodium carbonate Sodium hydroxide Phenolphthalein Sodium sulfate Hydrochloric acid Potassium carbonate Potassium hydroxide Ferric chloride Ammonium hydroxide Ammonium sulfate Copper (II) sulfate Ammonium carbonate BaCl2 H2SO4 Na2CO3 NaOH Na2SO4 HCl K2CO3 KOH FeCl3 NH4OH (NH4)2SO4 CuSO4 (NH4)2CO3 14 Name: Date: Period: Solution Mixing Chart: MIX SOLUTIONS OBSERVATIONS MIX SOLUTIONS 1+2 10 + 4 2+3 10 + 11 4+5 1 + 12 4+5+2 1+3+7 1+6 5 + 11 7+8 10 + 9 5+9 2+ 8 5+9+7 5 + 11 + 2 13 + 11 13 + 4 1 + 14 + 7 8+1+7 OBSERVATIONS 15 Name: Date: Period: Organize Data: Study the observations made until you see combinations of solutions that have the same observations. Groups of three solutions should not be compared with groups of two solution mixes. Record the observations that are the same and the solutions (by their number) that caused the same observations. Six are repeated, and two are not. (Hint- the 2 that are not are blue…) Repeated Observations Solution Combinations 1 2 3 4 5 6 Not Repeated Observations 1 2 Making Hypotheses: Similar observations indicate the same or a similar reaction. In this experiment you may assume that three similar observations represent a generalization. For example: (4 + 5), (5 + 9), and (5 + 11) all turned pink. The generalization would be that phenolphthalein turns pink in the presence of hydroxides. (The -OH group or the hydroxide, are what solutions 4, 9 and 11 all have in common). Using the chemical names and your organized data discover 5 OTHER generalizations. 1 2 3 4 5 16 Name: Date: Period: Predict & Test: From the five generalizations that you have made or discovered, write 2 procedures to show examples of two different generalizations. At least one of the solutions in your procedure can not be used once you have used it before. (There are different solutions on the side shelf). Use the solutions to test your procedures recording your observations and results. If your results agree with your rules they are considered to be positive; if the disagree they are negative. Indicate positive or negative for your conclusion. Procedure 1 Observations 1 Conclusion: Procedure 2 Observations 2 Conclusion: Questions: 1) To identify a sulfate solution the first step is to add barium ions from a barium solution. What will happen once the barium ions are added? 2) A carbonate solution will react the same way when barium ions are added to it. (Check you data to confirm this). What kind of solution could be added after the barium ions to distinguish between a sulfate and a carbonate solution? 3) What would you observe if you added this solution (answer to Q2) to the carbonate solution? 17 Name: Date: Period: Introduction to Graphing in Chemistry There are various types of graphs that can be made. However, it depends on the information you are working with, what type of graph best suits the data. If you are comparing two variables to each other a line graph works best. If you are comparing unrelated things, a bar graph would be well suited. A pie graph works best when you are comparing parts of a whole. When making a graph it is critical that the graph accurately depicts the data. This means you have to place the correct variable on the correct axis. The x-axis is for the independent variable or the variable that you can manipulate. The y-axis is for the dependent variable, or the variable whose outcome is dependent upon the other variable. The axes should always be labeled with the variables and include units when appropriate. Additionally, it is important that the increments on the axes are even. For example, you would want to use numbers such as 2,4,6,8,10 rather than 3,5,9 because the latter are not in even increments. The graph should fill the page provided. If it doesn’t, rescale the axes so that the graph is larger and will be a better predictive tool for analyzing the data. Graphs should always be shown as smooth lines or curves – NEVER play connect the dots. We want to show a smooth progression not a sawtooth pattern. For this reason, we tend to use lines of best fit, or curved lines which show a general trend in the data and can allow for us to analyze and interpret our data. Titles should be written in statement form demonstrating what the graph is about. Avoid the word ‘versus’ in your statement, and write it in a sentence where the independent variable is stated before the dependent variable. For example, ‘The effect of [independent variable] on [dependent variable]’ would work where the variables you are working with are inserted into the brackets. Lastly, USE A RULER! Sloppiness is acceptable. Equipment: 1) Broken Pieces of Spaghetti at random lengths 2) Electronic or Triple Beam Balance 3) Graph Paper Procedure: 1) Make a data table to record the lengths and masses of small pieces of spaghetti. 2) Measure the lengths of the pieces of spaghetti at your lab table. 3) Record your data that you obtain in your data table. 4) Measure the masses of the pieces of spaghetti at your lab table. 5) Record your data that you obtain in your data table. 6) Use the data you collected and construct a graph that best suits the data. Remember to include all the pertinent information you would find on a graph. 18 Name: Date: Period: Density Is a Periodic Property Introduction: Dmitri Mendeleev proposed the periodic law for the classification of elements in 1869-1871. After observing trends in the properties of elements when they were arranged in order of increasing atomic mass, Mendeleev made a startling prediction. He predicted the existence and properties of at least three undiscovered elements. Mendeleev saw what other scientists before him had missed-he saw what wasn’t there! Chemical Concepts: •Periodic law •Density • Group 14 elements • Period number Background: At the time Mendeleev proposed the periodic law, the foundation of the modern periodic table for the classification of elements, 63 elements were known. Their physical and chemical properties had been studied and their atomic masses measured. Mendeleev arranged the known elements in a calendar-like table of rows and columns in order of increasing atomic mass and repeating chemical properties. It is at this point; however, that Mendeleev made a giant leap of discovery-he suggested that there were some gaps or missing elements in the list of known elements. Among the Group 14 elements in Mendeleev’s classification scheme, carbon appeared in the second row, followed by silicon in the third row. Both tin and lead shared similar chemical properties with carbon and silicon and were also known at this time. Because of their high atomic masses, however, these metals were placed in later rows of Mendeleev’s Group 14 column of elements. In 1871, Mendeleev proposed that there existed an as-yetunknown element beneath silicon in the Group 14 elements. He named the missing element ekasilicon and predicted its physical properties (atomic mass, melting point, density, and specific heat). In 1886 the element germanium was discovered by the German chemist Clemens Winkler. In his report of the discovery, Winkler stated: “. . . There can be no longer any doubt that the new element is no other than the ekasilicon prognosticated fifteen years ago by Mendeleev.” Within 15 years of Mendeleev’s prediction of the existence of missing elements, three of the elements had been discovered, their properties in excellent agreement with those predicted by Mendeleev. Is it possible to recreate some of the excitement that followed the prediction and discovery of Mendeleev’s missing elements? Experiment Overview: The purpose of this experiment is to measure mass and volume data for silicon, tin, and lead, calculate their densities, and use these results to predict the density of germanium, Mendeleev’s “undiscovered” element in the Group 4 family of elements. The volume of the elements will be measured by water displacement (see Figure 1). 19 Name: Pre-Lab Questions: Date: Period: 1. One of the elements Mendeleev predicted was ekaaluminum, corresponding to a gap in the fourth row or period of the Group 13 elements, between aluminum and indium. The density of aluminum (period 3) is 2.70 g/cm3, that of indium (period 5) 7.31 g/cm3, and that of thallium (period 6) 11.85 g/cm3 Make a graph of period number on the x-axis versus density on the y axis for each of these elements. 2. Use your graph to predict the density of ekaaluminum. What known element in the modern Periodic Table corresponds to ekaaluminum? Look up the density of the modern element in a reference source and record its actual and predicted density values. 3. How do the actual and predicted density values compare? Calculate the percent error between the predicted and actual values for the density of ekaaluminum. Materials: Lead shot, Pb, 35 g Paper towels Silicon lumps, Si, 8 g Water Tin shot, Sn, 25 g Balance, centigram (0.01 g precision) Beakers, 50-mL, 3 Graduated cylinder, 25 mL Forceps or tongs Marking pencil or pen Tape Safety Precautions: Lead powder is extremely toxic by inhalation and ingestion, lead fumes and dust are possible carcinogens. Using lead shot does not present a powder or dust hazard. Do not work with lead powder. Silicon is flammable in powder form and is slightly toxic. Do not breathe or handle any fine silicon powder remaining on the bottom of the reagent bottle. Wear chemical splash goggles and chemical-resistant gloves and apron. Wash your hands with soap and water before leaving the laboratory. Procedure 1. Label three 50 mL beakers or small containers Si (silicon), Sn (tin) and Pb (lead). 2. Obtain approximately 8 g of silicon chunks in the appropriately labeled beaker. Measure the combined mass of the beaker plus solid to the nearest 0.01 g and record the value in the Data Table. (Note: This value is the initial mass for sample 1.) 3. Fill a 25 mL graduated cylinder approximately half-full with water. Measure the initial volume of water and record the value to the nearest 0.1 mL in the Data Table. 4. Using forceps or tongs, carefully add about one-third of the silicon chunks to the graduated cylinder. Add the solid slowly, so as to avoid splashing or breaking the glass cylinder. 5. Measure and record the new (final) volume of water plus solid in the graduated cylinder. 6. Measure and record the combined mass of the labeled beaker and remaining solid in the Data Table. (Note: This value is the final mass for sample 1.) 20 Name: Date: Period: 7. Repeat steps 4—6 twice with some of the remaining amount of solid in the beaker. Do NOT empty the graduated cylinder between samples. The final volume of the previous sample becomes the initial volume for the next sample. 8. Record all initial and final mass and volume data in the Data Table. There should be a total of three sets of mass and volume data (samples 1-3). 9. After all three trials have been completed, empty the water from the graduated cylinder. Carefully pour all the silicon chunks onto a paper towel and allow them to dry. Do not allow any of the solid to go down the drain. 10. Rinse the graduated cylinder with water. 11. Obtain approximately 25 g of tin shot in the appropriately labeled beaker. Measure the initial mass of the beaker plus solid to the nearest 0.01 g and record the value in the Data Table. 12. Repeat steps 3-10 using tin. Record all initial mass, final mass and volume data in the Data Table. 13. Obtain approximately 35 g of lead shot in the appropriately labeled beaker. Measure the initial mass of the beaker plus solid to the nearest 0.01 g and record the value in the Data Table. 14. Repeat steps 3-10 using lead. Record all initial mass, final mass and volume data in the Data Table. 15. Return the correctly labeled solids to your instructor for reuse. Data Table: Element Sample Initial Mass (g) Final Mass (g) Mass of Solid (g) Initial Volume (mL) Final Volume (mL) Volume of Solid (mL) 1 Silicon 2 3 1 Tin 2 3 1 Lead 2 3 21 Name: Post-Lab Calculations: Date: Period: 1. Complete the Data Table: Calculate both the mass (initial mass -final mass) and volume (final volume -initial volume) for each trial. Record these results in the Data Table. 2. It would be advisable to add to the table above or construct a new table for the information from your calculations. The table should include density for each trial, an average density for each element and a plus or minus value for each average density. Note: The density of a solid is usually reported in units of g/cm 3. 3. Using the mass and volume data, calculate the density of each tria. 4. Calculate the average value (mean) of the densities for each element, silicon, tin, and lead. Record all results in the Results Table. Use the range of density values for each element to estimate “plus-or-minus” (±) error for each average (e.g., if your densities are 6.8 g/cm3, 7.0 g/cm3 and 7.2 g/cm3 your average would be 7.0 g/cm3. Your plus or minus value would be ±0.2 g/cm3). 5. On a graph, plot the period number of Si, Sn, and Pb on the x-axis versus the average density of each element on the y axis. Using a ruler or straightedge, draw a “best-fit” straight line through the data points. Use this “best-fit” straight line to predict the density of germanium. 6. Look up the actual density of germanium in a reference source and calculate the percent error between the predicted and actual values (see Pre-Lab Question #3). 22 Name: Date: Period: Law of Conservation of Mass Experiment The experiment will explore whether matter is created or destroyed during a chemical reaction. Materials solutions of 0.1M - NaOH, CuSO4, NH4OH, and Na2CO3 1 graduated cylinder 4 plastic cups balance Procedure Label the four cups to contain the solutions (one each for NaOH, CuSO 4, NH3 (aq), and Na2CO3). You can do this by placing a paper towel under each cup and labeling it with the chemical formula. Trial 1 1. Use a graduated cylinder to measure about 60 mL of the NaOH solution, and then pour the solution into its designated cup. 2. Clean out the graduated cylinder to measure about 60 mL of the CuSO4 solution, and then pour the solution into its designated cup. 3. Carefully place the two solutions (in their cups) on the balance. Mass the solutions and their containers together and record their combined mass in the data table. 4. Pour the NaOH solution into the container with the CuSO4 solution. Allow the solutions to mix. Describe what happens in the data table. 5. Mass both containers and the mixture again. Record the new mass. a. Did the mass change? 6. Clean out the cups & dispose of solutions by following the directions indicated by your teacher. Trial 2 7. Use a graduated cylinder to measure about 60 mL of the NH4OH solution, and then pour the solution into its designated cup. 8. Clean out the graduated cylinder to measure about 60 mL of the CuSO4 solution, and then pour the solution into its designated cup. 9. Carefully place the two solutions (in their cups) on the balance. Mass the solutions and their containers together and record their combined mass in the data table. 23 Name: Date: Period: 10. Pour the NH4OH solution into the container with the CuSO4 solution. Allow the solutions to mix. Describe what happens in the data table. 11. Mass both containers and the mixture again. Record the new mass in the data table. a. Did the mass change? 12. Clean out the cups & dispose of solutions by following the directions indicated by your teacher. Trial 3 13. Use a graduated cylinder to measure about 60 mL of the Na2CO3 solution, and then pour the solution into its designated cup. 14. Clean out the graduated cylinder to measure about 60 mL of the CuSO4 solution, and then pour the solution into its designated cup. 15. Carefully place the two solutions (in their cups) on the balance. Mass the solutions and their containers together and record their combined mass in the data table. 16. Pour the Na2CO3 solution into the container with the CuSO4 solution. Allow the solutions to mix. Describe what happens in the data table. 17. Mass both containers and the mixture again. Record the new mass in the data table. a. Did the mass change? 18. Clean out the cups & dispose of solutions by following the directions indicated by your teacher. Data and Observations Solutions Mixed Mass prior to mixing solutions (g) Mass after mixing solutions (g) NaOH and CuSO4 Description of Reaction: Solutions Mixed Did the mass change? Mass prior to mixing solutions (g) Mass after mixing solutions (g) NH4OH and CuSO4 Description of Reaction: Did the mass change? 24 Name: Solutions Mixed Date: Mass prior to mixing solutions (g) Period: Mass after mixing solutions (g) Na2CO3 and CuSO4 Description of Reaction: Did the mass change? Analysis Questions: 1) What evidence did you see in each reaction to know for certain that a chemical reaction occurred? (Recall the evidence of a chemical change). 2) How did the final mass of each system compare to the initial mass of each system? Be specific for each reaction. 3) Based on how you answered question 2, for each reaction – do any of the reactions (appear to) violate the Law of Mass Conservation? If yes, state which mixtures (be specific). 4) What could be a possible reason why, one or more of the reactions appeared to violate the Law of Mass Conservation? (Come up with a reason even if all of your reactions did not appear to violate the law). Extension Question: 5) When a log burns, the resulting ash material has less mass than the unburned log did. Explain whether this loss of mass violates the Law of Mass Conservation. 25 Name: Date: Period: Artifact Ages 26 Name: Date: Period: 27 Name: Date: Period: 28 Name: Date: Period: Mole Lab Directions: 1. Carefully examine each vial – write a good descriptive physical description of the element in the space provided in the data table. 2. To calculate the mass of the sample in each vial, determine the mass of the sealed vial and its contents then subtract the mass of the empty vial and its cap (written at the balance) from the total mass. Write this final value in the data table. a. Since each vial contains 1 mole of an element, the difference is the mass of one mole of the element (or you could say it’s the molar mass of the element). 3. Take the determined mass of the element and look up the mass on the periodic table. Record the element name and symbol for the element that has the mass that is closest to the mass you received in the lab. 4. Take the “molar mass” of each element that you determined by obtaining the mass and determine the amount of atoms in the sample. Show your work stations 1 -6. Place your answers in the data table. For the remaining stations, you do not have to show your work, but you must have the answer in the data table. Data Table: Station # Physical Description Final Mass of Element Element Name Element Symbol Number of Atoms 1 2 3 4 5 6 7 29 Name: Station # Date: Physical Description Final Mass of Element Element Name Period: Element Symbol Number of Atoms 8 9 10 11 12 Answer the following questions: a. Which of the elements are metals? b. Which of the elements are metalloids? c. Which of the elements are non-metals? d. How do the physical properties of metals differ from non-metals? e. Does each sample have the same mass? Why or why not? 30 Name: Date: Period: Atomic Mass of Vegium Purpose: This lab is designed for students to determine the relative isotope abundance and the average atomic mass of the fictitious element, vegium. Background information: Isotopes are atoms of the same element that have different masses due to different numbers of neutrons. The average atomic mass reported on the periodic table is the weighted average of all isotopic masses of that element. The weighted average takes into account both the mass and the relative abundance of each isotope as it occurs. In the scientific community, scientists use a mass spectrometer to determine the average atomic mass of an element. The mass spectrometer works by separating particles by mass and then measuring the relative abundance of each. (The relative abundance allows them to compare the amount of each isotope against the other isotopes of an element). From this data, the weighted average is calculated and reported as the average atomic mass. The weighted average allows for the fact that the amount of each isotope of an element is not equal and there is a difference in the mass of each atom due to a change in the number of neutrons present in the nucleus. Lab: In this lab you will examine the element known as “Vegium”. Vegium consists of three isotopes: cornium, beanium, and peaium. You will simulate the work of the mass spectrometer by separating and counting counting the amount of each isotope you have in a sample. Then you will determine the mass of each individual isotope, and eventually use the data and calculations to determine the average atomic mass of Vegium. Procedure: Step 1: Separate the beans, peas, and corn kernels. Mass all the beans, then all the peas, and finally all the corn and record your data for each on the data table. Step 2: Count all the beans, peas, and corn kernels. Record your data for each on the data table. 31 Name: Date: Period: Step 3: Divide the total mass of each isotope by the number of each isotope to get the average mass of each isotope. For the total column for step 3, calculate it just like you calculated the average mass of each isotope. Step 4: Divide the number of each isotope by the total number of “atoms” (total in step 2), to get the relative abundance. Step 5: Multiply the relative abundance of each isotope by 100 to get the percent abundance. Step 6: Multiply the relative abundance from step 4 by the average mass of each isotope (obtained in step 3) to get the relative weight of each isotope. Step 7: Add the relative weights to get the average mass of all particles in vegium, the atomic mass. Step 8: Return your sample of vegium in its weigh-boat. Vegium: 1) Cornium 2) Beanium 3) Peaium Interesting isotopes – if I do say so myself. 32 Name: Date: Period: Data Table: BEANS PEAS CORN TOTAL (add the previous 3 columns together to get this value; except in step 3) Mass of each isotope Number of each isotope Average mass of each “atom” Relative abundance Percent abundance Relative weight Analysis Questions: 1) Which of your data (in the table) can be obtained through measuring? Which had to be calculated? Be specific. 2) What is the difference between the percent abundance and the relative abundance? 33 Name: Date: Period: 3) What is the difference between the average mass you calculate in step 3 and the relative weight you calculated in step 6? 4) Compare the average atomic mass (relative weight) you received for your vegium sample with two other lab groups. Record their values below: a. Group 1: _____________ b. Group 2: _____________ c. Your value: ____________ Are they similar? How would the difference be affected if larger samples were used? 5) If the accepted average atomic mass of vegium is 0.158g. Determine your percent error: % error = (|Experimental Value - Accepted Value| / Accepted Value) x 100 6) Describe sources of error in the procedure/sample. 34 Name: Date: Period: Flame Tests Fingerprints are unique to each person, so is the color of light emitted by an element heated in a flame. You will explore the characteristic color that is emitted by calcium, copper, potassium, sodium, strontium, lithium, and barium. When substances are exposed to heat, the atoms absorb the heat energy. When this occurs the absorbed energy excites the electrons and allows them to “jump” to excited energy levels. The natural tendency when electrons jump to an excited energy level is to return to their ground state. When this transition occurs a particle of light, a photon, is emitted. Electrons may return to their ground state in a single step or they may take multiple steps, in which they emit a photon each time they take a step towards their original ground state. The energy of each emitted photon is equal to the difference in energy between the excited state and the state to which the electron returns. The energy emitted determines the color of light observed in the flame. We can use the following equation to determine the energy of a photon: ∆E = hc λ Where ∆E is the difference in energy between the two energy levels (unit – joules) and h is Planck’s constant at 6.626x10-34 J/s, and c is the speed of light at 2.998x108 m/s. Lambda (λ) is the wavelength of light in meters. The visible light spectrum falls between 700nm and 400nm, where 700nm is red and 400nm is violet. There are regions in which a certain color can be obtained and we can estimate a representative wavelength for the color. See table. Wavelength Region (nm) 400-425 425-480 480-500 500-560 560-580 580-585 585-650 650-700 Representative Wavelength (nm) 410 470 490 520 565 580 600 650 Color Violet Blue Blue-Green Green Yellow-Green Yellow Orange Red Materials: A wooden splint, soaked, in each of the following chemical salts: calcium, copper (II), lithium, potassium, sodium, strontium, barium, unknown 1. Bunsen burner, match book, beaker with water 35 Name: Date: Period: Pre-lab: Fill in the blanks: When an atom absorbs energy, the electrons move from their ___________________ state to an ___________________ state. When an atom emits energy, the electrons move from a(n) ___________________ state to their ___________________ state and give off ___________________. Is a flame test a qualitative and quantitative test? ___________________ Procedure: 1) Obtain a tray and a paper towel. On the paper towel, list each salt across the bottom. 2) Obtain one wooden splint, soaked in its salt, and place it on the paper towel above the label. 3) Set up your burner, and light it. 4) Wait until all students are ready to begin. The instructor will turn off the lights so that the results are more visible. 5) Carefully place a wooden splint into the flame. Carefully move the wooden splint back and forth, and watch for a unique color flame to be produced. 6) Record the color of the splint. 7) Place the splint in the beaker containing water. 8) Continue steps 5 – 7 until all splints have been burnt. 9) Discard wooden splints and matches in the trash can, and empty water into the sink. 10) Please put all materials used away properly. TABLE of RESULTS Metal Ion Color of Flame λ (nm) λ (m) ∆E (J) Calcium Barium Strontium Copper (II) Sodium Lithium Potassium Unknown 1 In the above table, when you have completed the flame tests complete the following: Obtain the wavelength in nanometers from table 1 on the first page of the lab. Fill in the wavelength based on the color you observed in the lab. Convert the wavelength from 36 Name: Date: Period: nanometers into meters and place that value in the next column. Finally, calculate the change in energy by using the equation on the first page of the lab and your wavelength (m). Place that answer in the chart in the column labeled ∆E. Post Lab Questions 1) In the space below, show the calculation (your work with units) for ∆E of calcium. 2) What element(s) makes up the unknown substance(s) you tested? 3) What evidence can you cite that indicates that the color produced was due to the metal ion in the compound? 4) The alkali metals, cesium and rubidium, were discovered based on their characteristic flame color. Cesium is named after the sky and rubidium after a beautiful gemstone. What colors of light do you think these colors give off when heated in a flame? 5) How does the information obtained from flame tests relate to real world applications of these elements? (Think about entertainment). 37 Name: Date: Period: REACTIVITY OF ALKALINE EARTH METALS Introduction: The elements in group 2A of the periodic table are called the alkaline earth metals. The name was given to these elements because they were first isolated from compounds in which they were combined with oxygen. They were called “earths” by early chemists, and later the word “alkaline” was added because they formed basic or alkaline solutions in water. This can be tested in the lab by adding a solution of phenolphthalein which turns pink when in the presence of a base. The alkaline earth metals have two valence electrons, which they tend to give up easily; therefore they are quite reactive. They are never found free in nature and they must be protected from both air and water, in order to remain in their unreacted state. Magnesium and calcium are obtained in their elemental state through a process called electrolysis, and then are stored in air tight containers. The purpose of the lab is to test the reactivity of magnesium and calcium, along with two other alkaline earth metals. You will then compare the reactivity of each with aluminum, which is part of group 3A on the periodic table. Pre – Lab: 1) What are some common properties (characteristics) of the alkaline earth metals? 2) In a solution how would know if the solution is alkaline (or basic)? 3) Why are alkaline earth metals very reactive in nature? Materials: Goggles Aprons 3 test tubes Forceps Distilled water Micropipets Bunsen burner Wire gauze square Scoopula 10 ml Graduated Cylinder Tongs Matches Steel wool Phenolphthalein Magnesium ribbon Calcium metal Aluminum foil 38 Name: Date: Period: SAFETY: DO NOT TOUCH THE CALCIUM WITH YOUR HANDS. IF YOU ARE EXPOSED IMMEDIATELY FLUSH WITH WATER. DO NOT HAVE AN OPEN FLAME WHEN EXPOSING THE CALCIUM TO WATER, THIS COULD CREATE AN EXPLOSIVE GAS. DO NOT LOOK DIRECTLY AT THE MAGNESIUM WHEN BURNING – USE PERRIFERAL VISION. KEEP LONG HAIR TIED BACK! Procedure: 1) Put on your safety gear: goggles and apron. 2) Retrieve one piece of calcium, magnesium, and aluminum from the front lab table. Place each in a test tube. 3) Place the test tubes in the test tube rack when you return to your lab table. Calcium 4) 5) 6) 7) Measure out 3 mL of distilled water in a graduated cylinder. Slowly pour the 3 mL of distilled water into the test tube with the calcium. Observe all reactions, and record. When the reaction stops, check to see if any metal remains. If it does, add 1 mL of water to the test tube again. 8) When all the metal is reacted, place 1 drop of phenolphthalein into the test tube. 9) Record all observations. Magnesium 10) Retrieve the magnesium strip from the test tube, and clean it thoroughly with the steel wool. (It should be really shiny) 11) Place the magnesium strip back into the test tube. 12) Measure out 3 mL of distilled water in a graduated cylinder. 13) Slowly pour the 3 mL of distilled water into the test tube with the magnesium. 14) Observe all reactions, and record. 15) Place 1 drop of phenolphthalein into the test tube. 16) Record all observations. 17) Remove the magnesium strip from the test tube, and dry it off thoroughly. 18) Set aside for later. Aluminum 19) Measure out 3 mL of distilled water in a graduated cylinder. 20) Slowly pour the 3 mL of distilled water into the test tube with the aluminum. 21) Observe all reactions, and record. 22) Place 1 drop of phenolphthalein into the test tube. 23) Record all observations. 24) Remove the aluminum strip from the test tube, and dry it off thoroughly. 39 Name: 25) Set aside for later. Date: Period: Clean Up 26) Empty the contents of your calcium test tube into the beaker marked waste by your instructor. Rinse all test tubes in the sink. Flush with lots of water. Clean test tubes using detergent solution, and a brush. PART B 27) In two separate test tubes, measure 3 mL of distilled water in a graduated cylinder and place in each. 28) Light the Bunsen burner. Magnesium 29) Using the forceps, pick up the magnesium metal strip. 30) Place the strip into the flame, and look away. 31) As soon as it lights, pull it out of the flame and let it continue to burn. When the flame goes out, drop it into one of the test tubes with distilled water. 32) Place 1 drop of phenolphthalein into the test tube. 33) Record all observations. Aluminum 34) Using the forceps, pick up the magnesium metal strip. 35) Place the strip into the flame. Attempt to light. It may not catch on fire, but it may start to charcoal after a while. This is okay. 36) After a periods of time (when it starts to turn black) drop it into one of the test tubes with distilled water. 37) Place 1 drop of phenolphthalein into the test tube. 38) Record all observations. 40 Name: Date: Period: Data Table: Step Calcium + Water Observations Calcium + Water + Phenolphthalein Magnesium + Water Magnesium + Water + Phenolphthalein Aluminum + Water Aluminum + Water + Phenolphthalein Magnesium burning Burned Magnesium + Water + Phenolphthalein Aluminum burning Burned Aluminum + Water + Phenolphthalein Post Lab Questions: 1) Was the reaction of calcium in water an exothermic reaction, meaning energy was released? If yes, how do you know? 2) Did any of your solutions turn pink after you added a drop of phenolphthalein to the solution? If yes, which ones? 41 Name: Date: Period: 3) Looking at the metals you used. Are the alkaline earth metals more or less reactive than aluminum? Support your answer with details. 4) Look at your observations between magnesium and calcium, in relation to their position on the periodic table. As you move from top to bottom on the periodic table, does the reactivity of the metals increase or decrease? Support your answer. 5) Based on your answer to question 4, would strontium (Sr) be more or less reactive than calcium? 6) Which metal, Calcium or Aluminum would be more likely to be used in structural materials? Explain why. 42 Name: Date: Period: Exploring the Halides The elements in Group 7A of the periodic table are nonmetals called the halogens. The word Halogen, comes from two Greek words that mean “salt” and “former.” There are a total of five members of this group; fluorine, chlorine, bromine, iodine, and astatine. Each halogen can react with a number of different metals to form compounds, called halides. For example sodium reacts with chlorine to form the compound called sodium chloride. The first four halogens from classes of halides with easily recognizable names: Fluorides – metal + fluorine Chlorides – metal + chlorine Bromides – metal + bromine Iodides – metal + iodine In this investigation you will observe chemical reactions of small quantities of four halides with specific solutions. You will use your observations of these reactions to determine which halide is present in a solution containing one or more unknowns. Pre-lab Questions: 1) What are the five halogens and what is the chemical symbol of each? 2) What are fluorides, chlorides, bromides, and iodides? 3) What method will you use to study halide reactions? Materials: goggles apron microtitration plate (24 well) micropipets with the following solutions: sodium chloride (NaCl) sodium bromide (NaBr) sodium iodide (NaI) silver nitrate (AgNO3) sodium thiosulfate (Na2S2O3) ammonium hydroxide (NH4OH) starch sol’n bleach (NaClO) toothpicks (about 20 qty) 43 Name: Date: Period: Caution: ** Wear goggles and aprons at all times! ** Handle all chemicals carefully! ** Do not inhale fumes from bleach or ammonium hydroxide! ** Never mix bleach and ammonium hydroxide! **Silver nitrate causes brown stains on hands and clothing so be careful not to touch, spill, or splash it. Procedure: Step 1: In the microtitration plate drawn below, place five drops of each solution in each row, as indicated by the drawing. A B C D 1 2 3 4 5 6 44 Name: Date: Period: In column B, see arrow, add 2 drops of silver nitrate to each well (1 – 5). Mix thoroughly with a toothpick. Record the observations on the data table provided on page 6. Detail color and if a precipitate forms. If no reaction occurs, write NR in the data table. In the same column, add 2 drops of ammonium hydroxide solution, and mix thoroughly with a toothpick. Record the observations on the data table provided on page 6. Detail color and if a precipitate forms. If no reaction occurs, write NR in the data table. In column C, see arrow, add 2 drops of silver nitrate to each well (1 – 5). Mix thoroughly with a toothpick. Record the observations on the data table provided on page 6. Detail color and if a precipitate forms. If no reaction occurs, write NR in the data table. In the same column, add 5 drops of sodium thiosulfate solution, and mix thoroughly with a toothpick. Record the observations on the data table provided on page 6. Detail color and if a precipitate forms. If no reaction occurs, write NR in the data table. In column D, see arrow, add 2 drops of starch solution to each well (1 – 5), and then add 2 drops of bleach to each well (A – E). Mix thoroughly with a toothpick. Record the observations on the data table provided on this page. Detail color and if a precipitate forms. If no reaction occurs, write NR in the data table. 45 Name: Date: Data Table Well Solution 1 2 3 4 5 NaF NaCl NaBr NaI Unknown Period: Column 1 Column 2 Column 3 Column 4 Ca(NO3)2 AgNO3 + NH4OH AgNO3 + Na2S2O3 Starch + Bleach White precipitate N.R. N.R. N.R. N.R. N.R. N.R. NO REACTION NO REACTION NO REACTION NO REACTION Post Lab Questions Answer each of the following by using the lab data, pre-lab information and text book. 1) Look at the reaction results for sodium fluoride. Do they follow the same pattern as the other halides? Explain any differences. 2) Based on your observations, describe the precipitates formed by the reactions of the halides with silver nitrate. Be specific. 46 Name: Date: Period: 3) Which of the precipitates formed with silver nitrate dissolved when ammonium hydroxide was added? 4) Which of the precipitates formed with silver nitrate dissolved when sodium thiosulfate was added? 5) How did the halides react with the starch solution? Be specific. 6) How did the halides react with the bleach solution? Be specific. 7) What is the unknown halide? 8) How did you determine this? 47 Name: Date: Period: CHEMICAL BONDS Chemical compounds are combinations of atoms held together by chemical bonds. These chemical bonds are of two basic types—ionic and covalent. Ionic bonds result when one or more electrons from one atom or group of atoms is transferred to another atom. Positive and negative ions are created through the transfer of these electrons. In covalent compounds no electrons are transferred; instead electrons are shared by the bonded atoms. The physical properties of a substance, such as melting point, solubility, and conductivity, can be used to predict the type of bond that binds the atoms of the compound. In this experiment, you will test six compounds to determine these properties. Your compiled data will enable you to classify the substances as either ionic or covalent compounds. OBJECTIVES Compare the melting points of six solids. Determine the solubility of the solids in water and in ethanol. Determine the conductivity of water solutions of the soluble solids. Classify the compounds into groups of ionic and covalent compounds based on the properties observed. Summarize the properties of each group (ionic vs. covalent). SAFETY Always wear safety goggles, gloves, and a lab apron to protect your eyes and clothing. If you get a chemical in your eyes, immediately flush the chemical out at the eyewash station while calling to your teacher. Know the location of the emergency lab shower and eyewash station and the procedures for using them. Do not touch any chemicals. If you get a chemical on your skin or clothing, wash the chemical off at the sink while calling to your teacher. Do not taste any chemicals or items used in the laboratory. Never return leftovers to their original container; take only small amounts to avoid wasting supplies. Do not heat glassware that is broken, chipped, or cracked. Use tongs or a hot mitt to handle heated glassware and other equipment because hot glassware does not always look hot. When using a burner, confine long hair and loose clothing. If your clothing catches on fire, WALK to the emergency lab shower and use it to put out the fire. 48 Name: Date: Period: MATERIALS • 24-well microplate • Burner • Calcium chloride • Citric acid • Conductivity tester (not needed) • Ethanol • Goggles • Iron ring • Lab apron • Lauric acid • Potassium iodide • Ring stand • Safety goggles • Sodium chloride • Sucrose • Thin-stemmed pipets (2) • Wire gauze • Metal tray 49 Name: Date: Period: PROCEDURE 1. Put on safety goggles and a lab apron. 2. Before you begin, write a brief description of each of the six substances in Table 1. 3. Place a metal tray on an iron ring attached to a ring stand. Position the ring so that it is just above the tip of a burner flame. Light the burner for a moment to check that you have the correct height. Then extinguish it. 4. Place a few crystals of sucrose, sodium chloride, lauric acid, calcium chloride, citric acid, and potassium iodide in separate locations on the metal tray atop the wire gauze. Do not allow the samples of crystals to touch. 5. For this experiment, it is not necessary to have exact values for the melting point. The lid will continue to get hotter as it is heated, so the order of melting will give relative melting points. Light the burner and observe. Note the substance that melts first by writing a 1 in Table 1. Record the order of melting for the other substances. 6. After 3 min, record an n in Table 1 for each substance that did not melt. Extinguish the burner. Allow the metal tray and wire gauze to cool while you complete the remainder of the experiment. 7. Put a few crystals of each of the white solids in the top row of your microtitration plate. Repeat with the second row. Add 10 drops of water to each well in the top row. Do not stir. Record the solubility of each substance in Table 1. Use ‘yes’ and ‘no’ as your observations. 8. Add 10 drops of ethanol to each well in the second row of the microtitration plate. Do not stir. Record the solubility of each substance in Table 1. Use ‘yes’ and ‘no’ as your observations. 9. THIS WILL BE DONE BY THE TEACHER. Test the conductivity of each water solution in the top row by dipping both electrodes into each well of the microtitration plate. Be sure to rinse the electrodes and dry them with a paper towel after each test. If the bulb of the conductivity apparatus lights up, the solution conducts electric current. Record your results in Table 1. 10. Clean the microtitration plate with soap and water with a test tube brush. Wash your hands thoroughly before you leave the lab and after all work is finished. 50 Name: Date: Period: TABLE 1: CHARACTERISTICS OF COMPOUNDS Substance Description of Compound Melting Point Solubility in H2O Solubility in Ethanol Conductivity Calcium chloride Citric acid Lauric acid Potassium iodide Sodium chloride Sucrose ANALYSIS & CONCLUSION 1. Organizing Results: Group the white substances (write their names down) into two groups based on the properties (Description of Compound, Melting Point, Solubility in H 2O, Solubility in Ethanol, Conductivity) you observed. 2. Organizing Results: Keeping the groups in mind from number one, make a list the properties of each group. (See page 193 of your text for assistance). 51 Name: Date: Period: 3. Inferring Conclusions: Use your textbook and your experimental data to determine which of the groups consists of ionic compounds and which consists of covalent compounds. State the substances which belong in each type of compound. 4. Relating Ideas: Write a statement to summarize the properties of ionic compounds and another statement to summarize the properties of covalent compounds using the information you received in your lab and from your textbook. 52 Name: Date: Period: 53 Name: Date: Period: 54 Name: Date: Period: 55 Name: Date: Period: 56 Name: Date: Period: 57 Name: Date: Period: 58 Name: Date: Period: Weighing: A Means of Counting Objectives: 1) Measure masses of common compounds, objects, and minerals. 2) Calculate the number of moles and atoms from experimental masses. Introduction: You can often measure how much of something you have by counting the individual objects present. For instance, if you wanted to know how many pennies are in your pocket or how many pencils are in your book bag, you would simply count them. In chapter 7 you are learning that in chemistry there is a specific name for the number of atoms, ions or molecules present. One mole of a substance is equal to 6.022x1023 atoms, ions or molecules of that substance. You also know that you can “count” the number of moles by massing the substance. Purpose: In this lab you will measure the masses of samples that are commonly found. You will use your results as a means of counting the atoms, ions, and molecules in your samples. You will also extend your base knowledge by considering common objects that can be considered pure, like chalk and polystyrene peanuts. You will measure the masses of various substances and find the number of atoms, ions or molecules in each. Equipment: Balance, plastic spoon, sodium chloride, water, sucrose, silicon dioxide, calcium carbonate, polystyrene peanut, sulfur, plumbic sulfide, and ferric oxide. Procedure: 1) Mass one level teaspoon of sodium chloride, water, and sucrose. Record the value in the data table. 2) Mass the silicon dioxide, calcium carbonate, and polystyrene peanut. Record the value in the data table. 3) Mass the sulfur, plumbic sulfide, and ferric oxide. Record the value in the data table. 4) Determine the molar mass for each substance and record the value in the data table. 5) Calculate the number of moles, the number of moles for each element in the sample, and the number of atoms present in each element for all samples. SHOW YOUR WORK!! You may use the last page and additional sheets of notepaper. 59 Name: Date: Data Table: Name Formula Sodium chloride NaCl Water H2O Sucrose C12H22O11 Silicon dioxide SiO2 Calcium carbonate CaCO3 Mass (g) Molar Mass (g/mol) Moles in sample Period: Moles of each element Grams of each element 60 Name: Name Formula Mass (g) Polystyrene peanut C7H8 Sulfur S8 Plumbic sulfide PbS2 Ferric oxide Fe2O3 Molar Mass (g/mol) Date: Moles Moles of each in element sample Period: Grams of each element Data Table Analysis Question: 1) Looking at sodium chloride, water, and sucrose, which had the greatest number of moles present in one teaspoon? 61 Name: Date: Period: Ions and Solubility Introduction What do stalagmites and stalactites found in caverns have in common with the deposits found on old water faucets? How were many minerals, now mined as ores, originally formed? The answers to both questions can be found in a study of precipitates. If a positive ion (cation) of a dissolved salt reacts with the negative ion (anion) of a different compound to form a new salt with low solubility, chemists say that a precipitate has formed. Purpose To determine which ions react to produce precipitates by analyzing data regarding mixtures of ionic compounds. Safety Considerations Wear protective glasses and an apron at all times. Avoid skin contact the solutions. Dispose of all solutions in the containers provided by your teacher. Wash your hands before leaving the laboratory. Pre-Lab Write the formulas for the following compounds: 1. Silver nitrate ______________________ 2. Barium nitrate ______________________ 3. Calcium nitrate ______________________ 4. Copper (II) nitrate ______________________ 5. Zinc nitrate ______________________ 6. Lead (II) nitrate ______________________ 7. Potassium nitrate ______________________ 8. Iron (III) nitrate ______________________ 9. Sodium carbonate ______________________ 10. Sodium chloride ______________________ 11. Sodium hydroxide ______________________ 62 Name: 12. Sodium sulfate Date: ______________________ 13. Sodium phosphate ______________________ 14. Sodium oxalate ______________________ 15. Sodium iodide ______________________ 16. Sodium thiosulfate ______________________ Period: Procedure 1. Place a clean plastic sheet over the data grid similar to the one at the end of this laboratory activity. 2. To each section of horizontal Row A (A1 through A8) add two drops of 0.1 M silver nitrate solution. 3. As in Step 2, add FIVE drops of the solutions listed to each of the sections indicated: To Row B, add 0.1 M barium nitrate. To Row C, add 0.1 M calcium nitrate. To Row D, add 0.1 M copper(II) nitrate. To Row E, add 0.1 M zinc nitrate. To Row F, add 0.1 M lead(II) nitrate. To Row G, add 0.1 M potassium nitrate. To Row H, add 0.1 M iron(III) nitrate. 4. To the vertical Column 1 (A1 through H1), add two drops of 0.1 M sodium carbonate. 5. As in Step 4, add FIVE drops of the solutions listed to each of the vertical columns indicated: To Column 2, add 0.1 M sodium chloride. To Column 3, add 0.1 M sodium hydroxide. To Column 4, add 0.1 M sodium sulfate. To Column 5, add 0.1 M sodium phosphate. To Column 6, add 0.1 M sodium oxalate, Na2C204. To Column 7, add 0.1 M sodium iodide. To Column 8, add 0.1 M sodium thiosulfate, Na2S2O3. 63 Name: Date: Period: 6. Observe carefully to determine which combinations of solutions produced precipitates. In your data table, record each combination of ions that showed the formation of a precipitate. Record the color, texture, and other observations for each. 7. Dispose of chemical wastes and clean your plastic sheet as instructed by your teacher. 8. Wash hands thoroughly before leaving the laboratory. Data Grid Ag+ A Ba2+ B Ca2+ C Cu2+ D Zn2+ E Pb2+ F K+ G Fe3+ H CO32- Cl- OH- SO42- PO43- C2O42- I- S2O32- 1 2 3 4 5 6 7 8 Data Analysis, Concept 1. How would you tell another student how to decide whether a precipitate has formed when two solutions are mixed? Use examples from the activity to help you in this explanation. 2. Which cation(s) formed precipitates with all its anions horizontally across in Columns 1 through 8? 3. What anion is found in all solution combinations in this activity? What cation is common to all the solution mixtures? 64 Name: Date: Period: 4. List the names of the pairs of reagents that produced each precipitate in vertical Column 5. 5. Analyze your data regarding the solubility behavior of carbonate CO 32-; sulfate, SO42-; and iodide, I- State your conclusion to match the following sample conclusions: All chlorides are soluble except silver chloride. 65 Name: Date: Period: Law of Definite Composition Purpose: To determine the formula and the percent composition of a copper sulfide compound formed through synthesis. Procedure: LAB TABLE 1) Clean and thoroughly dry a porcelain crucible and its cover over a hot flame (blue) by holding them with the crucible tongs. 2) Cool for two minutes. 3) Mass the crucible and cover to the nearest .01 gram. Record this in the data table. 4) Mass a 10 cm piece of fine copper wire. Record the mass in the data table to the nearest .01 gram. 5) Place the copper in the crucible. 6) Re-mass the crucible, copper, and cover. Record the mass in the data table to the nearest .01 gram. 7) Add .50 gram of flowers of sulfur to the crucible and copper wire. This mass does not need to be recorded because it is in excess and will burn off as sulfur dioxide. FUME HOOD 8) Place the crucible with contents and cover on a pipestem triangle that is set up in the fume hood. 9) Heat the covered crucible and contents for as long as you can see flames from the burning sulfur coming out from under the lid of the crucible. 10) After the flames cease continue to heat for two to three minutes. 11) Using the crucible tongs, carefully remove the lid and check it for sulfur residue or burning. If this is present continue to burn until all sulfur has burned off. 12) Using the crucible tongs, carefully remove the lid and then the crucible from the pipestem triangle. Place the crucible and cover on a watch glass that has been covered with aluminum foil. 13) Let stand until cool. (may have to sit overnight) 14) Mass the crucible, contents and lid to the nearest .01 gram and record on the data table. Data: Mass (g) Crucible & Cover Copper Wire Crucible, Cover & Cu Wire Crucible, Cover & Cu Cmpd. 66 Name: Date: Calculations: Show all work, with units and labels. Period: 1) Calculate the mass of the copper in the compound. 2) Calculate the mass of the sulfur in the compound. 3) Calculate the moles of copper in the compound. 4) Calculate the moles of sulfur in the compound. 5) Calculate the percent by mass of the copper in the compound. 6) Calculate the percent by mass of the sulfur in the compound. 7) What is the ratio of moles of copper to moles of sulfur in the compound? 8) Use the mole ratio to determine the formula and name of the compound. Questions: Write in complete sentences. 1) Which element (Cu or S) was the limiting reagent in this lab experiment? How do you know? 2) What happened to the excess element? 3) How did you increase the potential for acid rain by doing this experiment? 67 Name: Date: Period: Percent Composition and Formula of a Hydrate Wear safety glasses/goggles and aprons when performing this lab activity. PROCEDURE: 1. Mass a clean, dry crucible to maximum accuracy of the balance. (Data # 1) 2. By placing it into the crucible, mass out 2.50 g - 3.50 g of cupric sulfate hydrate. It should be a fine granular consistency, not in chunks. Record new mass. (Data # 2) 3. Place the crucible on a pipestem triangle which is supported by a small ring on a ring stand. 4. Heat gently until the cupric sulfate hydrate turns all one color. If the sample starts turning brown or dark gray around the edges, reduce the flame height or move the wire ring two inches higher. Record all observations. (Data # 3) 5. Once all of the cupric sulfate hydrate is all one color. Turn off the Bunsen burner and allow the crucible to cool for 2 minutes. 6. Remove the crucible from the pipestem triangle, using the crucible tongs and place it in the dessicator. Allow the crucible to cool to room temperature (about 7-10 minutes). 7. Remove crucible from the dessicator and mass. Record the mass. (Data # 4) 8. IF TIME PERMITS, repeat steps 3 – 6. 9. Remove the anhydrous cupric sulfate and place it into a small beaker. Hold the beaker in your hand and add about five drops of water to the beaker. Record your observations. ( Data # 5) DATA: #1) Mass of crucible: __________________ #2) Mass of crucible & cupric sulfate hydrate: __________________ #3) Observations: ________________________________________________________________ _______________________________________________________________________________. #4) Mass of anhydrous cupric sulfate: __________________ #5) Observations: ________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________. 68 Name: Date: CALCULATIONS. Show all work with units. Period: 1. Calculate the percent of water in the hydrate. 2. From the mass of the water lost in heating and the mass of the anhydrous cupric sulfate determine the mole ratio of the water to the anhydrous cupric sulfate. 3. Write the formula for the hydrate of the cupric sulfate, from your results. ________________________________________________________________ QUESTIONS: 1. What is a hydrate? ________________________________________________ 2. Use a reliable sources to determine the most likely formula of the hydrate. ____________ 3. Which is more stable? (anhydrous cupric sulfate or the hydrate) ___________________________________________________________ 4. How did part 9 of the procedure & data # 5 support your answer for question 5? ___________________________________________________________________ ___________________________________________________________________ 5. What does anhydrous mean? ________________________________________ 6. Blue cobalt chloride turns pink when the relative humidity of the air is high. Explain why. 69 Name: Date: Period: Balancing Chemical Equations Lab Activity Objectives: 1) Write chemical equations from the given chemical reaction. 2) Balance each chemical reaction. 3) Make observations based on each chemical reaction completed. Directions: 1) Write and balance the chemical equations for each of the following chemical reactions. 2) Verify your reaction with your teacher. 3) Go to the indicated lab station to test your reaction. a. Take the pipette containing each chemical and place five drops of the first chemical listed in the reaction in the watch glass. b. To the watch glass, add five drops of the second chemical in your reaction. c. Record your observations. Be descriptive with each of your observations. If you do not see any change indicate there were no visual indicators seen. d. Rinse the watch glass off under the water faucet, rinsing the solution down the drain thoroughly. Dry the watch glass and make sure everything is in order for the next lab group. Materials: Watch Glass Chemicals o Aluminum sulfate o Ammonium hydroxide o Barium nitrate o Calcium chloride o Cobalt (II) nitrate o Copper (II) nitrate o Copper (II) sulfate o Iron (III) chloride o Lead (II) nitrate o Phosphoric acid o Potassium carbonate o Silver nitrate o Sodium bicarbonate o Sodium chloride o Sodium hydroxide o Sodium iodide o Sodium phosphate o Sodium sulfate o Sulfuric acid o Zinc metal Safety goggles Aprons 70 Name: Date: Period: Pre – Lab Question: 1) Given the following chemical reaction, which is partially balanced: K4Fe(CN)6 + 6 H2SO4 + 6 H2O K2SO4 + FeSO4 + 3 (NH4)2SO4 + 6 CO How many of each of the following components do you have present on each side: Reactants: Products: _____ K _____ K _____ Fe _____ Fe _____ C _____ C _____ N _____ N _____ H _____ H _____ O _____ O _____ SO4 _____ SO4 To balance the reaction, what coefficient should be used, and in front of which chemical formula would you place it? Write both the coefficient and the chemical formula in the space below. Chemical Equations: 1) Sodium bicarbonate and phosphoric acid react to form sodium phosphate, carbon dioxide, & water. a. Observations of chemical reaction: 2) Barium nitrate reacts with sulfuric acid to produce barium sulfate and nitric acid. a. Observations of chemical reaction: 3) Sodium hydroxide & copper (II) sulfate react to produce copper (II) hydroxide & sodium sulfate. a. Observations of chemical reaction: 4) Aluminum sulfate and sodium hydroxide react to form aluminum hydroxide and sodium sulfate. 71 Name: Date: Period: a. Observations of chemical reaction: 5) Sodium phosphate and calcium chloride react to form calcium phosphate and sodium chloride. a. Observations of chemical reaction: 6) Potassium carbonate and sulfuric acid react to form potassium sulfate, carbon dioxide, and water. a. Observations of chemical reaction: 7) Cobalt (II) nitrate reacts with sodium hydroxide to form cobalt (II) hydroxide and sodium nitrate. a. Observations of chemical reaction: 8) Iron (III) chloride reacts with sodium sulfate to form sodium chloride and iron (III) sulfate. a. Observations of chemical reaction: 9) Ammonium hydroxide and copper (II) sulfate to form copper (II) hydroxide and ammonium sulfate. a. Observations of chemical reaction: 10) Sodium phosphate and iron (III) chloride react to form sodium chloride and iron (III) phosphate. a. Observations of chemical reaction: 11) Iron (III) chloride reacts with sodium hydroxide to form iron (III) hydroxide and sodium chloride. a. Observations of chemical reaction: 12) Zinc metal reacts with lead (II) nitrate to form zinc nitrate and lead. 72 Name: Date: Period: a. Observations of chemical reaction: 13) Silver nitrate reacts with sodium chloride to produce sodium nitrate and silver chloride. a. Observations of chemical reaction: 14) Sodium iodide and copper (II) nitrate react to produce copper iodide and sodium nitrate. a. Observations of chemical reaction: 73 Name: Date: Period: Classifying Chemical Reactions Objective: In this experiment, you will observe example reactions representing the four main classifications of chemical reactions. You will record your observations and answer questions regarding each of the reactions. Part I: Procedure: A. Obtain a piece of magnesium ribbon, approximately 10cm long. Roll the Mg into a loose ball and place it in a clean, dry crucible. Record the mass of both the Mg and crucible. Record a description of the Mg ribbon. B. Set up the ring stand, ring, and pipestem triangle. Place the crucible in the pipestem triangle. Light the Bunsen burner and heat the crucible and Mg. When the Mg starts to glow, turn out the burner and allow the Mg continue to burn until it stops burning. C. Record your observations of the product. Once the crucible cools, mass the product and the crucible. D. Add a few drops of water to the product in the crucible. Waft the smell from the crucible to detect an odor. E. Clean out the crucible and dry it thoroughly. Observations/Data: Mass of crucible/Mg ribbon: ______________ Description of Mg: Mass of crucible/product: _____________ Description of product: Did you observe a change in mass? _________ Why or why not?_________________ _______________________________________________________________________ Did you detect an odor? ____________ What substance is responsible for the odor? __________________________ What is the chemical formula for the substance? __________ There are two primary gases present in the air. What are they? _______________ If each gas reacts separately with the Mg, two different substances are produced. 74 Name: Date: Period: What are the first two chemical reactions in this experiment? Once the products were formed, these products react with water. What are the final two balanced chemical reactions in this experiment? Part 2: Procedure: A. Obtain a piece of 16cm glass tubing with a rubber stopper attached and two test tubes. Set up the ring stand, test tube clamp, and burner as shown in the diagram. B. Place a very small amount of cupric carbonate into one of the test tubes. Insert the rubber stopper from the glass tubing into the test tube. Place the test tube in the test tube clamp. Note the color of the cupric carbonate. C. In the second test tube add limewater (Calcium hydroxide) to the test tube until it is about 2/3 the way full. Place the open end of the glass tubing into the test tube with the limewater. Hold this in place with your hand. D. Light the burner under the test tube with the cupric carbonate in it. Heat the bottom of the test tube. Record all observations. E. Once the cupric carbonate completely changes color, turn off the burner. Remove the limewater test tube from the glass tubing. F. Empty the contents, and clean thoroughly. Set aside for the experiments in part 3. Observations/Data: Color of cupric carbonate: ______________ Observations of the reactions: 75 Name: Date: Period: Two reactions occurred with this experiment. The cupric carbonate broke down into its smaller components, and the calcium hydroxide reacted with the carbon dioxide produced by the decomposition of the cupric carbonate. Write the two balanced chemical reactions. Part 3: Procedure: A. Using the same materials from part 2 of the experiment, obtain 5mL of 3.0M hydrochloric acid and pour into one of the test tubes. B. Place the test tube with the hydrochloric acid into the test tube holder as shown in the diagram. C. Obtain a few small pieces of “mossy” zinc. D. Prior to placing the zinc into the test tube containing the hydrochloric acid, make sure you have the glass tube and empty test tube ready. E. Drop the pieces of the zinc into the test tube with the hydrochloric acid. F. Quickly attach the rubber stopper/glass tube into this test tube with the open end of the glass tube going upwards. Cap the open end of the glass tube by sliding the empty test tube down over it. G. Touch the bottom of the test tube with the hydrochloric acid and zinc. You will also see a gas being emitted through the glass tube and into the empty test tube. H. After two minutes, slowly lift the test tube (collecting the gas) off the glass tube, and quickly place your thumb over the open end. Light a match and slowly move your hand and the test tube close to the match. Remove your thumb from the test tube. I. Clean up thoroughly. Observations/Data: Description of the reaction: 76 Name: Date: Period: Was the reaction endothermic or exothermic? _______________________ Write the chemical reaction that occurred. What gas formed? _____________ What happened with the lit match and gas filled test tube? Write the chemical reaction that occurred with that test. Part 4: Procedure: A. Using two clean test tubes, place 4mL of ferric chloride hexahydrate into one of the test tubes. B. In the second test tube, place 4mL of sodium hydroxide. C. Slowly pour the ferric chloride hexahydrate into the test tube containing the sodium hydroxide. Record your observations. D. Place the products formed in the waste container in the fume hood. E. Clean up thoroughly, and put all materials away properly. Observations/Data: Description of the reaction: 77 Name: Date: Period: Write the chemical reaction that occurred in this experiment. Conclusion: What indicators that a chemical reaction occurred are present in these four experiments? 78 Name: Date: Period: Double Displacement Reactions This experiment will enable you to identify a few unknown solutions by noting their characteristic reactions with other known solutions. The seven solutions are: silver nitrate barium nitrate sodium phosphate copper (II) nitrate sodium sulfate sodium carbonate ferric chloride In order to learn certain characteristics of reactions of the preceding solutions, mix them in pairs using the microtitration plate. For each chemical use 10 drops; once you add the second chemical, mix the solution and record your results. One good way to do this is to fill in the observation on page 3. For each reaction, write a balanced equation. (See page 4 for this). Indicate if the reactants and products are in solution (aq) or precipitates (s) by placing these subscripts behind each formula in every equation. All reactions are double displacement reactions. Use the table above to identify the unknown solution or solutions your instructor will give you. Record all observations you observe from mixing part of the unknown solution with portions of the solutions above. Record which solutions you used. Someone else should be able to read your observations and repeat your work. Record you data, unknown number or letter, and your conclusion at the bottom of the 1st page. Along with writing balanced equations for each reaction you will identify the precipitate formed in the reaction. You will do this by using an arrow pointing downward or marking it with the subscript (s) for solid. That means that the chemical marked is insoluble in water therefore does not dissolve, it comes out of solution. All soluble chemicals will be labeled with the subscript (aq) and the equation will be balanced, example below: Ba(NO3)2(aq) + K2SO4(aq) BaSO4(s) + 2KNO3(aq) Ions are separated by water molecules. The ions are so small that they are invisible to the human eye but are capable of reflecting light in such a way that some of the solutions have color. 79 Name: Date: Period: DATA TABLE AgNO3 Ba(NO3)2 Cu(NO3)2 FeCl3 Na2SO4 Ni(NO3)2 AgNO3 X Ba(NO3)2 X X Cu(NO3)2 X X X FeCl3 X X X X Na2SO4 X X X X X Ni(NO3)2 X X X X X X X X X X X Na2CO3 X Na2CO3 X Unknown # ______ Observations: ________________________________________ Conclusion: What chemical substance is it? __________________ Unknown # ______ Observations: ________________________________________ Conclusion: What chemical substance is it? __________________ 80 Name: Date: Period: Reactions: Solve the double displacement reactions, use the solubility rules & show phases, and balance each reaction. 1) AgNO3(aq) + FeCl3(aq) 2) AgNO3(aq) + Na2SO4(aq) 3) AgNO3(aq) + Ni(NO3)2 (aq) 4) AgNO3(aq) + Na2CO3(aq) 5) Ba(NO3)2(aq) + FeCl3(aq) 6) Ba(NO3)2(aq) + Na2SO4(aq) 7) Ba(NO3)2(aq) + 8) Ba(NO3)2(aq) + Na2CO3(aq) 9) Cu(NO3)2(aq) + 10) Cu(NO3)2(aq) + Na2SO4(aq) 11) Cu(NO3)2(aq) + Ni(NO3)2(aq) 12) Cu(NO3)2(aq) + Na2CO3(aq) 13) FeCl3(aq) + Na2SO4(aq) 14) FeCl3(aq) + Ni(NO3)2 (aq) 15) FeCl3(aq) + Na2CO3(aq) Ni(NO3)2(aq) FeCl3(aq) 81 Name: Date: Period: Colored Precipitates – Net Ionic Equations Binary ionic compounds exhibit a variety of properties. Some dissolve easily in water, while others are insoluble. Some are brightly colored compounds; many others are white. You can use characteristic properties of known substances to determine the identity of an unknown by comparing the properties of a known substance with those of the unknown. In this experiment, you will carry out some double-displacement reactions and observe the characteristic colors of precipitates. You will use your experimental data to identify unknown substances. OBJECTIVES 1. Observe displacement reactions in which precipitates are formed. 2. Compare chemical and physical properties of substances. 3. Relate observations to the identification of unknown solutions. 4. Infer a conclusion from experimental data. MATERIALS • 0.1 M Co(NO3)2 • 0.5 M CuCl2 • 0.5 M FeCl3 • 0.2 M Ni(NO3)2 • • • 0.1 M NaOH mystery solutions 1 and 2 microtitration plate 1. Always wear safety goggles and a lab apron to protect your eyes and clothing. If you get a chemical in your eyes, immediately flush the chemical out at the eyewash station while calling to your teacher. Know the locations of the emergency lab shower and eyewash station and the procedures for using them. 2. Do not touch any chemicals. If you get a chemical on your skin or clothing, wash the chemical off at the sink while calling to your teacher. Make sure you carefully read the labels and follow the precautions on all containers of chemicals that you use. If there are no precautions stated on the label, ask your teacher what precautions you should follow. Do not taste any chemicals or items used in the laboratory. Never return leftovers to their original containers; take only small amounts to avoid wasting supplies. 3. Call your teacher in the event of a spill. Spills should be cleaned up promptly, according to your teacher’s directions. PROCEDURE 1. Using your microtitration plate, place 20 drops of sodium hydroxide, NaOH, in seven wells in the plate. For best results, all the drops should be the same size. 2. To the first well, add 5 drops of cobalt (II) nitrate solution, Co(NO 3)2. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. 3. To the second well, add 5 drops of copper (II) chloride solution, CuCl 2. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. 82 Name: Date: Period: 4. To the third, add 5 drops of iron (III) chloride, FeCl3. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. 5. To the fourth, add 5 drops of nickel (II) nitrate, Ni(NO3)2. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. 6. To the fifth well, add 5 drops of mystery solution 1. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. 7. To the sixth well, add 5 drops of mystery solution 2. Observe what happens. Record your observations and the physical properties of the substances formed in the Data Table. DISPOSAL 8. Clean all apparatus and your lab station. Return equipment to its proper place. 9. Dispose of the solutions in the microtitration plate by rinsing them thoroughly down the drain with a large amount of water. You can let the water run for a few minutes while you wash out the microtitration plate with the soap solution. Dry the plate to the best of your ability. 10. Wash your hands thoroughly before you leave the lab and after all work is finished. DATA TABLE: Co(NO3)2 Ni(NO3)2 CuCl2 FeCl3 Mystery 1 Mystery 2 Observations: ANALYSIS & CONCLUSIONS: The above reactions are all double displacement reactions, in which they were reacted with sodium hydroxide. 1. Write a balanced double displacement reaction for each. Use the solubility rules to determine aqueous and solid (precipitate) for your reaction and indicate using the phase symbols in your equation. 2. Then write the total ionic and the net ionic equation for each reaction. Reaction 1: Total Ionic Equation: Net Ionic Equation: 83 Name: Date: Period: Reaction 2: Total Ionic Equation: Net Ionic Equation: Reaction 3: Total Ionic Equation: Net Ionic Equation: Reaction 4: Total Ionic Equation: Net Ionic Equation: 1. Which of the net ionic equations that you wrote describe the reactions of the two mystery solutions? a. Mystery Solution 1: b. Mystery Solution 2: 2. How did you make the determination for each of the mystery solutions? 3. Were the characteristic colors caused by the positive metal ions or the negative ions present in the compounds? a. How did you come to this conclusion? 84 Name: Date: Period: Factors Affecting Reaction Rate OVERVIEW Chemical reactions occur at different rates. In this experiment you will consider some of the key factors that influence the rate of a reaction: nature of reactants - particle size temperature concentration catalysts SAFETY Portions of this lab may only be carried out under the supervision of a teacher Safety goggles must be worn when working with acids. According to the collision theory, the rate of a reaction depends on the frequency of collisions between reacting particles. The more frequent the collisions, the faster the rate of the reaction. However, in order for the collisions to be effective, the particles must collide with sufficient energy (activation energy). Furthermore, the particles must collide with the proper orientation. The factors that will be examined in this lab influence reaction rate by either increasing how often collisions occur or by making collisions more effective. PURPOSE To examine factors that increase reaction rate 85 Name: Date: Period: EQUIPMENT AND MATERIALS PROCEDURES Part 1. Effect of Particle Size Part 1. Effect of Particle Size on Reaction Rate solid marble chips (calcium carbonate) calcium carbonate powder balance 2 test tubes 1M HCl (approx 10 mL per group) Part 2. Effect of Temperature 3 Alka Seltzer tablets 3 250-mL beakers water at three temperatures – with ice, room temperature, warm (around 70C) Part 3. Effect of Concentration 1M HCl, 5 mL per group 3M HCl, 5 mL per group 6M HCl, 5 mL per group 3 pieces of zinc metal, each approx 1 cm 1 cm 3 test tubes Part 4. Effect of a Catalyst 3% hydrogen peroxide, H2O2 – 30 mL per group 0.1 M iron(III) nitrate, Fe(NO3)3 0.1 M iron (III) Chloride, FeCl3 0.1 M sodium chloride, NaCl 0.1 M calcium chloride, CaCl2 0.1 M potassium nitrate, KNO3 Solid Manganese (IV) Oxide 100-mL graduated cylinder 10-mL graduated cylinder 6 test tubes per group 1. Obtain a piece of solid calcium carbonate, approximately 0.5 cm 2 cm. Find the mass of this sample, and place it in a test tube. 2. Using the balance obtain a sample of powered calcium carbonate that is close to the mass of your piece of solid calcium carbonate. Place this sample in the second test tube. 3. Place both test tubes in a test tube rack. Add 5 mL of 1M HCl to both test tubes. Be sure to wear your safety goggles. 4. Observe both test tubes and record your observations in the data table. Part 2. Effect of Temperature 1. Half fill three 250-mL beakers with water. In one beaker add several ice cubes. A second beaker will contain water at room temperature. In the third beaker add water that has been heated to about 70C. 2. Record the water temperature in the three beakers, and then add an Alka Seltzer tablet to each. 3. Record the time it takes for the Alka Seltzer tablet to completely dissolve. 4. If after 10 minutes your alka seltzer tablet is not dissolved, record “did not dissolve” in the data table. 86 Name: Date: Period: Part 3. Effect of Concentration 1. Pour 5 mL of each of the three HCl solutions into separate test tubes. Place the test tubes in a test tube rack. 4. Mix each tube by swirling the test tube or gently stirring with a clean stirring rod. 2. Add one piece of zinc to each test tube. 5. Observe each solution, noting the production of any gas bubbles that form. Record each reaction rate as fast, slow, very slow, or none in your data table. 3. Record the time you added the zinc to the tubes, and the time each reaction stops. Also record your observations for each tube. Part 4. Effect of a Catalyst In this part of the lab you will determine which substance/substances act as a catalyst for the decomposition of hydrogen peroxide. RESULTS Record your results for each part of the lab in the data tables provided on the following page. 1. Place 5-mL of 3% H2O2 solution into each of 6 test tubes. 2. Add 5 drops of each of the following solutions to separate test tubes: 0.1 M FeCl3 0.1 M NaCl 0.1 M Fe(NO3)3 0.1 M CaCl2 0.1 M KNO3 3. Place several grains of solid Manganese (IV) oxide into the last test tube. 87 Name: Date: Period: Questions 1. a. What effect does particle size have on the rate of a chemical reaction? b. Write the reaction you carried out in part 1 and site evidence from your experimental observation (in your data table) to support your answer to 1a. 2. a. What effect does temperature have on the rate of a chemical reaction? b. Site evidence from your experimental observation to support your answer to 2a. 3. a. What effect does concentration have on the rate of a chemical reaction? b. Write the reaction you carried out in part 3 and site evidence from your experimental observation to support your answer to 3a. 88 Name: Date: Period: 4. a. Which substances in part 4 acted as catalysts in the reaction? b. What affect does a catalyst have on the rate of a chemical reaction? 5. List 4 factors that affect the rate of a chemical reaction. RESULTS Table 1. Effect of Particle Size on Reaction Rate Substance Tested Observations powdered calcium carbonate marble chips Table 2. Effect of Temperature Water Condition Water Temperature (C) Time to Completion cold room temperature warm 89 Name: Date: Period: Table 3. Effect of Concentration Acid Concentration Start Time Time at Completion Observations 1 M HCl 3 M HCl 6 M HCl Table 4. Effect of a Catalyst Possible Catalysts FeCl3 NaCl Fe(NO3)3 CaCl2 KNO3 MnO2 Reaction Rate 90 Name: Date: Period: MOLE RATIO IN A CHEMICAL REACTION Procedure: 1. Mass a clean, dry 205mL beaker to the nearest .01 grams. Record the mass. 2. Place about 9 grams of the cupric sulfate hydrate into the beaker. Record mass. (This is your excess amount). 3. Add approximately 200mL of hot/warm water to the beaker; stir to dissolve the cupric sulfate. Record your observations. 4. Mass about 1.5 grams of steel wool (iron) to the nearest .01 grams. Record the mass. 5. Carefully add the steel wool to the cupric sulfate solution. Stir the contents intermittently until it disappears and another substance takes its place. Record all changes observed. 6. Set up the filtering apparatus with the funnel, ring stand, and filter paper. Mass the filter paper. Record mass. 7. Place a 250mL beaker under the funnel to catch the drainage. 8. Allow all of the precipitate to settle to the bottom of the beaker. Decant (drain) the solution off the precipitate and into the funnel. The liquid that goes through the filter paper is called the filtrate. The solid particles that remains in the filter paper is called residue. When all the solution has been decanted off – rinse the precipitate into the filter paper using the wash bottle and rubber policeman on the stirring rod. Make sure to get as much of the precipitate into the filter paper as possible. 9. Remove filter paper from funnel and place on a labeled watch glass. Place watch glass and filter paper in the fume hood to dry overnight. 10. Day 2 – Mass the filter paper and residue to the nearest .01 grams. Record the mass. Data Table: Mass of dry beaker: Mass of cupric sulfate Mass of steel wool: Mass of filter paper: added to beaker: Observations (Pro 3): Observations (Pro 5): Mass of filter paper & residue: 91 Name: Date: Period: Questions: Show all work, equations, and units for full credit. Circle your answers in your calculations. 1. Write the balance chemical reaction that occurred. 2. Determine the moles of iron used in the experiment (mass-mole). 3. Determine the grams of copper produced (subtraction of data). 4. Determine the moles of copper produced (mass-mole). 5. Based on your calculations, above, did you make ferric or ferrous ions? Give evidence to support your answer. 6. What visible evidence in the experiment indicated that copper sulfate was in excess and the iron what the limiting reagent? 92 Name: Date: Period: Synthesis of a Compound by Double Displacement Purpose of Lab: 1) To demonstrate synthesis of a compound. 2) To use stoichiometric relationships to calculate percent yield. Procedure: 1) Measure out 1 gram of sodium carbonate monohydrate to the nearest .01 grams. Record the mass in the data table. 2) Dissolve the sodium carbonate monohydrate in 40 ml of water in a beaker. 3) Calculate the amount of calcium nitrate tetrahydrate needed to react with the mass of sodium carbonate monohydrate you have measured out. Perform calculation in the data table. 4) Add 10% more of the calcium nitrate tetrahydrate to the calculated amount and mass it out. Record new mass in data table. 5) Dissolve the calcium nitrate tetrahydrate in 40 ml of water in a beaker. 6) Combine the two aqueous solutions of calcium nitrate and sodium carbonate by pouring the calcium nitrate into the beaker with the sodium carbonate. Write the balanced chemical reaction for the double displacement that occurred in the data table. 7) Set up the filtering apparatus, while the precipitate settles to the bottom of the beaker. 8) Mass the filter paper to the nearest .01 grams before you place it in the funnel. Record mass in data table. 9) Decant the liquid off of the precipitate by gently pouring it into the funnel. Be careful not to fill past the top level of filter paper. 10) Using the rubber “policeman” on the stirring rod decant the rest of the solution including the precipitate into the funnel. 11) Rinse out the beaker using the wash bottle to transfer the residue into the filter paper. Repeat as necessary. 12) Remove the filter paper from the funnel and place on a watch glass. Place the watch glass and filter paper in the fume hood or on your lab top for drying. 13) Clean up all lab materials, and wipe up any water. 14) When the filter paper is dry, re-mass the filter paper and the product to the nearest .01 grams. Record the mass on the data table. 93 Name: Date: Period: Data Table: Mass of Sodium Carbonate monohydrate Calculate the mass of the calcium nitrate tetrahydrate needed: Mass of filter Paper Mass of filter paper and product Add 10% to calculated amt of calcium nitrate tetrahydrate: Double Displacement Reaction: (2 pts) Questions/Calculations: 1) Calculate the actual yield of the product. Show work. (2 pts) 2) Calculate the expected yield of the product (calcium carbonate) based on the mass of the sodium carbonate monohydrate given. Show all work and units. (5 pts) 3) Calculate percent yield. Show all work. (3 pts) 4) Based on your percent yield, list three possible reasons for error. (3 pts) 94 Name: Date: Period: MASS-VOLUME & IDEAL GAS LAW CONSTANT LAB Procedure: 1. Cut a 3-4cm piece of magnesium ribbon and clean it with steel wool. Coil the magnesium ribbon. Mass the magnesium on the analytical balance to the tenth of a milligram. (.0001 g) Record your mass in the data table. 2. In the fume hood, measure 5mL of concentrated (12M) hydrochloric acid into a 50mL eudiometer tube. Be careful not to inhale the vapors of the acid. Rinse any excess acid that spills off the side of the eudiometer tube. 3. At your lab table, fill the tube to the top with room temperature water. Pour the water from a beaker very slowly so as not to mix the acid and water to any great extent. 4. Fill a tall (2L) cylinder with room temperature water and place the cylinder in the sink. Record the temperature of the water in the data table. 5. Tie a piece of thread to the magnesium ribbon, and tie this to a 1-hole stopper, leaving about 1 -2 inches of string between the stopper and the magnesium. 6. Place the stopper on the tube, so that the magnesium is immersed in the water. There should be no air trapped in the tube. If there is, remove the stopper and completely fill it with water so that there is no air pocket. Any air in the tube will cause a large error in your data. 7. Hold one finger over the hole of the stopper, invert the tube and place it in the cylinder filled with water. Do not remove your finger from the hole until the stopper is immersed. Observe the acid as it falls down through the water and comes in contact with the magnesium. Describe your observations in the data table. 8. When the reaction is completed record the temperature of the water in the cylinder. (This temp will be used at the temp of the gas in the eudiometer since it bubbled through this water). Record the temperature in the data table. 9. Raise or lower the eudiometer tube in the cylinder until the level of the water in the cylinder is equal to the level of the water in the eudiometer. (The water is slightly acidic since there was excess acid and the magnesium was the limiting reagent.) When the levels are equal the pressure of the atmosphere is equal to the pressure of the gas in the eudiometer tube. Record the volume of the gas in the eudiometer tube by reading the liquid level in the tube. Note which way the scale runs on the tube and then record the volume of the gas in the data table. 10. Read the barometer on the wall for the atmospheric pressure and record it in the data table. 11. Using a water vapor pressure table in your text book, record the water vapor pressure at the temperature of the gas in the data table. 95 Name: Date: Period: Data Table: Mass of Mg ribbon: Temp of gas: Temp of water: Volume of gas: Observations of rxn: Atmospheric pressure: Water vapor pressure: Calculations: 1. Calculate the pressure of the “dry” hydrogen gas. 2. Calculate the volume that the “dry” hydrogen gas would occupy at STP. a. b. c. d. e. f. P1= V1= T1= P2= V2= T2= 96 Name: Date: Period: 3. Using the volume of dry hydrogen calculated in #2, calculate the moles of hydrogen produced. 4. From the moles of hydrogen produced, and the balanced chemical equation, calculate the moles of magnesium that would be needed to produce this hydrogen. 5. Using the moles of magnesium calculated in # 4, calculate this mass of magnesium. 6. Compare the mass of magnesium you calculated above with the mass of magnesium you actually used. To do this, calculate percent error using the mass of magnesium you actually weighed out as the accepted value and the mass of magnesium you calculated in #5 as the experimental value. Accepted value - Experimental value x 100 Accepted value 7. List several possible sources of error in this experiment. 97 Name: Date: Period: Endothermic and Exothermic Reactions Many chemical reactions give off energy. Chemical reactions that release energy are called exothermic reactions. Some chemical reactions absorb energy and are called endothermic reactions. You will study one exothermic and one endothermic reaction in this experiment. In Part I, you will study the reaction between citric acid solution and baking soda. An equation for the reaction is: 3 CO2(g) + 3 H2O(l) + Na3C6H5O7(aq) H3C6H5O7(aq) + 3 NaHCO3(s) In Part II, you will study the reaction between water and calcium chloride. An equation for this reaction is: Ca 2+ (aq) + 2Cl- (aq) CaCl2(s) + H2O(aq) Another objective of this experiment is for you to become familiar with Logger Pro, a program you will use with nearly every experiment in this manual. In this experiment, you will use Logger Pro to collect and display data as a graph or table, analyze your experimental data values, and print a graph or data table. Figure 1 MATERIALS IBM-compatible computer Lab Pro Interface Logger Pro Stainless Steel Temperature Probe 50-mL graduated cylinder balance Styrofoam cup 250-mL beaker Citric Acid, H3C6H5O7, solution Baking Soda, NaHCO3 Water, H2O Calcium Chloride, CaCl2 98 Name: Date: Period: PROCEDURE 1. Obtain and wear goggles. Part I Citric Acid plus Baking Soda 2. Place a Styrofoam cup into a 250-mL beaker as shown in Figure 1. Measure out 30 mL of citric acid solution into the Styrofoam cup. Place a temperature probe into the citric acid solution. 3. Prepare the computer for data collection by opening “Exp 01” from the Chemistry with Computers experiment files of Logger Pro. The vertical axis has temperature scaled from -10 to 40°C. The horizontal axis has time scaled from 0 to 300 seconds. 4. Weigh out 10.0 g of solid baking soda on a piece of weighing paper. 5. The temperature probe must be in the citric acid solution for at least 45 seconds before this step. Begin data collection by clicking Collect . After about 20 seconds have elapsed, add the baking soda to the citric acid solution. Gently stir the solution with the temperature probe to ensure good mixing. Collect data until a minimum temperature has been reached and temperature readings begin to increase. You can click on Stop to end data collection or let the computer automatically end it after 300 seconds. 6. Dispose of the reaction products as directed by your teacher. 7. To analyze and print your data: • Click the Statistics button, . In the statistics box that appears on the graph, several statistical values are displayed for Temp 1, including minimum and maximum. In your data table, record the maximum as the initial temperature and the minimum as the final temperature. Close the statistics box by clicking the upper-right corner of the box. • To confirm the minimum and maximum temperatures, use the scroll bars in the Table window to scroll through the table to examine the data. Compare the minimum and maximum data points to those you recorded in the previous step. • Print a copy of the Table window. Enter your name(s) and the number of copies of the table. • You will often want to change the scale of either axis of the graph. There are several ways to do this. To scale the temperature axis from 0 to 25°C instead of the present scaling, click the mouse on the “40” tickmark at the top of the axis. In place of the “40”, type in “25” and press the Enter key. Notice that the entire axis readjusts to the change you made. Use the same method to change the “-10” tickmark to “0”. Note: A second option is to click the Autoscale button, . The computer will automatically rescale the axes for you. • You can also expand any portion of the graph by zooming in on it. Select the area you want to zoom in on. Do this by moving the mouse pointer to the beginning of this section of data—press the mouse button and hold it down as you drag across the curve, leaving a rectangle. Then click the Zoom In button, . The computer will now create a new, full-size graph that includes just the region inside the rectangle. You can reverse this action by clicking the Undo Zoom button, . 99 Name: Date: Period: • When you again collect data in Part II of this experiment, the data will be collected as Latest run, the most recent set of data you have collected. The original Latest run will be lost if it is not saved or stored. Choose Store Latest Run from the Data menu to store Latest as Run 1, then save or print it later. Note that the line for Run 1 is thinner than it was for Latest. To hide the curve of your first data run, click the Temperature vertical-axis label of the graph, and uncheck Run 1. Click OK . Part II Water Plus Calcium Chloride 8. Manually rescale the vertical axis to the original temperature scale of -10 to 40°C. To do so, click the mouse on the bottom tickmark and type in “-10”. Then click on the top tickmark and type in “40”. 9. Measure out 30 mL of water into the Styrofoam cup. Place the temperature probe into the water. 10. Obtain 10 grams of calcium chloride from the teacher. 11. Note: The temperature probe must be in the water for at least 45 seconds before this step. Begin data collection by clicking Collect . After about 20 seconds have elapsed, add the CaCl2 to the water. Gently stir the solution with the temperature probe to ensure good mixing. Caution: Do not breathe the vapors. Collect data until a maximum temperature has been reached and the temperature readings begin to decrease. 12. Dispose of the reaction products as directed by your teacher. 13. To analyze your Part II data: • Change the appearance of the graph by double-clicking anywhere on the graph bring up the Graph Options dialog. Check the box in front of Point Protector Every 1 Point—a point protector will now outline each data point on the graph. Click OK . • Instead of scrolling through the Table window in this trial, click the Examine button, . The cursor will become a vertical line. As you move the mouse pointer across the screen, the temperature and time values corresponding to its position will be displayed in the box at the upper-left corner of the graph. Scroll across the initial 34 points to determine the initial temperature. Record the initial temperature in the data table. Move the mouse pointer across the peak of the temperature curve to determine the maximum temperature, and record it as the final temperature in your data table. To remove the examine box, click the upper-right corner of the box. • It is also possible to calculate statistics just for a portion of your collected data. To do so, you must first select the data you are interested in. For example, you might want to find the average (or mean) of the first few data points to use as an initial temperature, instead of using the minimum value. Select the flat portion of the curve—move the mouse pointer to time 0 and drag across the flat part of the curve. Now click the Statistics button, , and note the mean temperature value in the statistics box on the graph. This value is the mean of only the selected data 100 Name: Date: Period: points. When you are done, click on the upper-right corner of the statistics box to remove it. 14. To print a graph of temperature vs. time showing both data runs: • Click the Temperature vertical-axis label of the graph. To display both temperature runs, check the Run 1 and Latest boxes. Click OK . • Label both curves by choosing Make Annotation from the Analyze menu, and typing “Endothermic” (or “Exothermic”) in the edit box. Then drag each box to a position near its respective curve. • Print a copy of the Graph window. Enter your name(s) and the number of copies of the graph you want. 15. Save the temperature and time data from both data runs. Choose Save As from the File menu and give the file a distinct name. As directed by your teacher, choose a location for the file, and click OK . DATA AND CALCULATIONS Part I Part II Final temperature, t2 ________°C ________°C Initial temperature, t1 ________°C ________°C Temperature change, ________°C ________°C OBSERVATIONS Processing the Data 1. Enter the values for T in the data table. 2. Tell which reaction is exothermic. Explain. 101 Name: Date: Period: 3. Which reaction had a negative Δt value? Is the reaction endothermic or exothermic? Explain. 4. For each reaction, describe three ways you could tell a chemical reaction was taking place. 1._____________________________________________________________ 2._____________________________________________________________ 3._____________________________________________________________ 5. Which reaction took place at a greater rate? Explain your answer. 6. A. Use the equation Qrxn = -(mc T) surr to calculate the heat of reaction of Reaction 1 (citric acid and sodium bicarbonate reaction.) Consider the solution in the cup to be the surroundings. Assume the density and specific heat of the citric acid solution are the same as that for water. 6B. Use Qrxn to calculate Hrxn for reaction 1. (Use the mass of NaHCO3 you massed out, and the Molar Mass of NaHCO3 To convert from Q rxn to Hrxn.) 102 Name: Date: Period: 6C. Write the thermochemical equation for reaction 1. Use correct formulas and subscripts, and place H rxn in the correct place. 7A. Use the equation Qrxn = -(mc T) surr to calculate the heat of reaction of Reaction 2 (dissolving Calcium Chloride): 7B. Use Qrxn to calculate H for reaction 2. (Use the mass of CaCl2 you massed out, and the Molar Mass of CaCl2 ). 7C. Write the thermochemical equation for reaction 2. Use correct formulas and subscripts, and place H in the correct place. 103 Name: Date: Period: 104 Name: Date: Period: 105 Name: Date: Period: 106 Name: Date: Period: 107 Name: Date: Period: 108 Name: Date: Period: 109 Name: Date: Period: 110 Name: Date: Period: 111