Honors Chemistry Unit 1 Early chemists describe the first dirt molecule What is chemistry? Elements to Memorize! Polyatomic Ions to Memorize! Chemistry Careers Scientific Method Observation Lab Lab Safety Lab Equipment Alchemy Lab 1 At the conclusion of this unit, the student will be able to: 1. 2. 3. 4. Identify and describe the development 6 branches of chemistry out of alchemy. Distinguish between pure research, applied research, and technology. Use the scientific method to solve various problems. Use appropriate safety/lab equipment and procedures in the science classroom We are looking for: 1. Ability to distinguish and identify various scenarios as organic, physical, biochem., analytical, inorganic, theoretical chemistry. 2a. Pure research is learning for the sake of knowing. 2b. Applied research is using the knowledge gained from pure research to solve a specific problem. 2c. Technology is using the knowledge gained from pure research to improve the quality of life. 3a. Identify a problem. 3b. Create a hypothesis. 3c. Identify the independent and dependent variables, and control. 3d. Write a procedure. 3e. Collect and analyze data/observations and distinguish between qualitative and quantitative observations. 3f. Formulate a conclusion. 4a. Identify the safety features of the room. 4b. Correctly light and adjust a Bunsen burner. 4c. Identify incorrect behavior in a lab scenario. 4d. Identify names and uses for lab equipment. 4e. Demonstration of safety procedures in the lab. 2 How Chemistry Began Throughout history people have tried environment to improve their way of life. to alter their Such “tinkering” has often lead to unexpected results. 4000 B.C. Mesopotamian Cultures Irrigation 2000 B.C. Egyptians Metallurgy and Embalming 400 B.C. Greeks Understanding of Matter 600 A.D. India Steel 1000 A.D. Chinese Gunpowder This “tinkering” has fulfilled two needs: To understand the world around them. To improve and protect our lives. 3 Chemistry 4 Research Research is done for different reasons. The type of research pursued is dependent uon what information is important/needed. Basic or Pure Research: The main goal of this type of research is to gain new knowledge about a chemical or process, just for the sake of knowledge. Chance discoveries can result from basic research. “I wonder what would happen if …” Applied Research: The main goal of this type of research is to solve a specific problem. Example: CFC’s (chloro fluor carbons) in refrigerants destroyed the ozone so chemists formulate new refrigerants. Technological Development: This type of research involves the making and use of products that improve the quality of life. Development can result from basic research. Example: Teflon coating. 5 Ag Li Al Mg Ar Mn As Mo Au N B Na Ba Ne Be Ni Br O C P Ca Pb Cd Pt Ce Ra Cl Rb Co Rn Cr S Cs Sb Cu Sc F Se Fe Si Fr Sn Ga Sr Ge Ti H U He V Hg W I Xe K Zn Kr 6 7 Introduction Polyatomic ions are charged molecules. The atoms within a polyatomic ion are usually very tightly bound together, so the ion retains its identity within ionic compounds and over the course of many chemical reactions. Because polyatomic ions are basic building blocks of so many ionic compounds, learning the names, charges, and formulas of the most common polyatomic ions is absolutely essential before many other skills can be mastered. Most common polyatomic anions occur in "families". All members of the family share the same central element and the same charge. There are three common types of variations within the family: Other Different members of the family can have different numbers of oxygens. Each member of the family can combine with hydrogen ions to partially neutralize their negative charge. Some members of the family can have sulfur substituted for oxygen. variations exist but are less common. Table of common polyatomic: Polyatomic Name Polyatomic Ion Ammonium NH4+ Hydronium H3O+ Acetate C2H3O2- Bromate BrO3- Bicarbonate HCO3- Chlorate ClO3- Hydroxide OH- Iodate IO3- Nitrate NO3- Permanganate MnO4- Carbonate CO32- Chromate CrO42- Sulfate SO42- Phosphate PO43- 8 Common naming practices If you can remember the formula of the ion whose name ends with ate, you can usually work out the formulas of the other family members as follows: modify stem name with: meaning examples per-, -ate same charge, but contains one more oxygen than perchlorate, ClO4- -ate form perbromate, BrO4- a common form, containing oxygen chlorate, ClO3- -ate nitrate, NO3sulfate, SO42-ite one less oxygen than -ate form chlorite, ClO2sulfite, SO32nitrite, NO2- hypo-, -ite same charge, but contains one less oxygen than hypochlorite, ClO- the -ite form hypobromite, BrO- Some anions can capture hydrogen ions. For example, carbonate (CO32- can capture an H+ to produce hydrogen carbonate HCO3- (often called bicarbonate). Each captured hydrogen neutralizes one minus charge on the anion. 9 NICK the CAMEL ate a CLAM for SUPPER in PHOENIX Ex) Underlined letter represents the symbol of the element. The consonants represent the number of oxygen present with the symbol. The vowels represent the number of negative charge. Underlined letter = N Number of consonants = 3 Number of vowels =1 represents oxygens represents charge NO3- Ex) Underlined letter = P Number of consonants = 4 Number of vowels =3 Nitrate represents oxygens represents charge PO43- Phosphate Camel Carbonate Clam Chlorate Supper Sulfate Another One!!! IZZY the BRAT CRAVED MINTS Izzy IO3- Iodate Brat Bromate Craved Chromate Mints Permanganate 10 Career Report Directions: Read the handout given to you about a career in chemistry and answer the following questions. You should use this information to write a job advertisement as a blog on my website. You must post your job advertisement to the blog by the end the day on ___________! You will respond to 3 jobs starting on _______________ You have until 3:00 on __________________ to respond to 3 jobs. See the blog for further instructions! 1. Name of chemical career 2. How much education/training do you need to qualify for this job? 3. How much money can I make doing this job? 4. Who is best suited for this job? 5. What is a typical day like working this job like? 11 12 Scientific Method 1. Define the problem You can’t solve a problem until you know exactly what the problem is 2. Collect background information What do I know and what will I need to know about the problem? 3. Formulate a hypothesis A possible solution to the problem – simple is better usually! 4. Test the hypothesis Perform an experiment to see if your hypothesis works. 5. Data Analysis Collect data and make good observations about what is happening. 6. Draw conclusions Evaluate what was found and let everyone who is interested know what you found. If it worked – GREAT! If it didn’t work – start again!! Terms of the Scientific Method Observation – Statement of fact Obtained by using one of the five senses Qualitative (words) / Quantitative (numbers) Inference – Attempts to make one think Is in the form of a question Hypothesis – An explanation that can be tested A prediction based on observations Must state the conditions (variables) and explains why a phenomenon is occurring. Can be an educated guess. 13 Law Set of related observations of nature. Generalizes a body of observations. Proven to be true in each and every case. Governs a simple or single action. Observation that will lead to the use of the scientific method to explain why the observation occurred. Many times expressed with mathematical equations. Example: When a gas is heated, it will expand. Theory – Explanation of why a set of related observations occurs. Based on proven hypotheses Verified by multiple groups of researchers Tries to explain a whole series of related phenomena Proven within reasonable doubt More complex than a law Example: The kinetic molecular theory is used to explain why a gas will expand when heated. Law (Simple Relationship) Inference Hypothesis Theory (Complex) Testing the Hypothesis Research Models limit the number of variables to two o Independent Variable – The condition that is to be studied. It will be changed in the experiment. It is controlled by the experimenter – "I control it". o Dependent Variable – It will be affected by the independent variable. It cannot be controlled by the experimenter; think results of the experiment. Control Group-The group that is represented in a normal situation; does not receive the experimental treatment. Experimental Group(s)-The group that receives the experimental treatment, the independent variable. Constants- all the other conditions that must remain the same (constant) for both groups. 14 Writing If / Then Hypothesis Statements The “IF” part of the statement: Mention Independent and dependent variables Link: are related, depend on each other, can be correlated The “THEN” part of the statement: Make an educated guess how they are related or what will happen in the experiment If Variable 1 and Variable 2 are related then state the relationship you believe exists between the two variables. Example: If plant growth and amount of water are related, then the plant will grow taller the more it is watered. Independent variable = water Dependent variable = plant growth 15 16 Chemistry Lab Experience "Scientific Method" Title: "Observing And Questioning I. Problem: How does a chemist develop his skills of observation and of developing hypotheses? II. Background Information: A natural characteristic of all human beings is curiosity. We have all wondered how a watch keeps time or how the automobile engine uses the energy stored in gasoline. To chemists, the questions always revolve around the basic composition of matter and how we can change it to benefit mankind. The more we learn about nature and how nature works, the more specific our questions can become. In this experiment, you will observe some changes in matter. You will then propose some questions you would like answered to gain more understanding about the changes. III. Hypothesis: In your own words what do you think will happen during this lab? IV. Test Hypothesis: A. Materials: spatula 150 mL beaker graduated cylinder “X” crystals liquid “Y” liquid “Z” metal foil stirring rod safety glasses B. Procedure: 1. Using the very tip of your spatula, fill the tip of your spatula with crystals of "X" and place them in a clean, dry 100-150 mL beaker. 2. Measure exactly 21.2 mL of liquid "Y" into your graduated cylinder. Use your dropper pipette with a little of "Y" in a beaker to make this exact. Bring this with your observation page to your teacher for grading. Make certain that you and your lab partner agree on the volume. You will lose 1 point for each 1-2 tenths you are over or short of the required amount of liquid. (4/2 points) 3. Add liquid "Y" to the beaker containing "X". Do not stir. Observe for about 3 minutes. Caution: These crystals are poisonous; avoid contact and rinse spills with plenty of water. 4. Stir the crystals until they dissolve completely. There should be enough of "X" to turn the color of "Y". 5. Obtain a piece of metal foil. The piece should be approximately 2 cm x 2 cm square. Use your ruler to estimate the size. 6. Loosely crumple the metal foil and place in into the beaker with the dissolved crystals. If the foil floats, press it down with a stirring rod. After the reaction is complete, discard the liquid and rinse the beaker with water. 7. Measure about 25 mL of liquid "Z" and place it into a clean 100/150 mL beaker. 17 8. Obtain another piece of metal foil. The piece should be approximately 2 cm x 2 cm square. Crumple it loosely and place it in liquid "Z". Caution: Liquid "Z" causes burns and can injure the eyes. Avoid contact and rinse any spills with plenty of water. Do not inhale fumes. The reaction starts slowly, so allow enough time for your reaction to go to completion. The following are to be written of a separate sheet of paper! V. Record Observations: Prepare a data table like the one demonstrated on the overhead. VI. Draw Conclusions: A. Questions: 1. Write 8 questions (inferences) that you would like answered about this experiment. 2. Write answers (hypotheses) for all 8 questions. 3. Describe two major barriers that prevent you from discussing and understanding the changes you saw in this experiment. B. Summary Paragraph 18 Safety Contract for Honors Chemistry The National Science Teachers Association urges that students be required to review and sign a contract that defines acceptable behavior in a school science setting. The purpose of this contract is to make the student aware of his/her responsibility for laboratory safety. Students should realize the implications of improper laboratory behavior. Courts have ruled that students can be just as guilty of negligence as teachers in laboratory accidents. These guidelines are to keep you and your classmates safe. I will: 1. 2. 3. 4. 5. 6. Follow all instructions given by the teacher. Protect eyes, face, hands, and body when involved in science experiments. Carry out good housekeeping practices. Know where to get help fast. Know the location of the first aid, eye wash, fire extinguisher and fire blanket. Conduct myself in a responsible manner at all times. I, _________________________, have read and agree to follow the safety regulations set forth above and below on this contract. I will closely follow the oral and written instructions provided by the teacher and/or school administration. Date: ______________ Student Signature: ____________________________ Date: ______________ Parent Signature: ____________________________ Laboratory Safety Rules 1. Wear proper eye protection at all times during laboratory activity. Let instructor know if you wear contact lenses. Know the location of the eye wash equipment. 2. Confine or tie hair that reaches the shoulders – hair is flammable! 3. DO NOT eat, drink or chew gum in the laboratory. Never taste anything unless specifically instructed to do so by the teacher. No chemicals are ever to be taken from the laboratory. 4. Never engage in horseplay or practical jokes. 5. Footwear should cover the whole foot. 6. Avoid inhaling chemical fumes. All chemicals are dangerous unless they are known to be otherwise. 7. The teacher is to be notified immediately in case of an accident, no matter how trivial it may appear. 8. Know the locations of the fire extinguisher, fire blanket, eye wash, safety shower, first aid kit and clinic. 9. Notify instructor immediately of any spills on your clothing. 10. Dispose of items as instructed by the teacher. Only certain chemicals can be put down the drain safely. 11. Never return chemicals to their original container, unless told to do so. 12. Never point the open end of a test tube being heated at anyone, including yourself. 13. Always add acid to water (AA). This is particularly true of concentrated sulfuric acid. 19 20 21 22 23 24 25 26 Name ___________________________________ Class Period__________ Safety Scenarios The diagram below and the diagram on the back, show students performing laboratory activities. Study each diagram and write in the spaces all of the proper and improper lab techniques you can pick out. Be prepared to discuss your answers. Picture 1 Proper Techniques Improper Techniques 1. 1. 2. 2. 3. 3. 4. 4.. 5. 5. 6. 6. 27 Picture 2 Proper Techniques Improper Techniques 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 6. 6. 28 Lab Safety Stories On a separate sheet of paper, list of all the safety violations for each story. Story #1 – there are at least 10 violations in this story. Mike was the first to arrive at the laboratory. He had just come from playing basketball and still had on his gym shorts and sandals. Wanting to finish early, he began to work on the assigned lab. Mike had not read the lab so he quickly skimmed the directions. He needed some water to prepare a solution. There was an unlabeled bottle of clear liquid on the bench, so he tasted it to see if it was water. It was bitter and burned his mouth. He spit the liquid out and dumped the bottle into the sink. After preparing his solution, he got out his lunch and began to eat while getting the balance out of the cupboard. When he put the balance on the lab bench, he knocked over the beaker containing the solution and it fell onto the floor and broke. He pushed the broken pieces under the bench and got another breaker out of the supply cabinet. He got bored so he took 2 bottles of chemicals off the teacher’s desk and put several drops of each chemical into a beaker. He used his finger to stir the mixture. He discarded the liquid in his beaker down the sink and then returned the beaker to his lab drawer. 29 Story #2 – there are at least 6 violations in this story. Kate decided to do the experiment right away. She put her books, lunch and purse on one side of the lab bench so she could work on the other half. The lab called for her to heat some water. She turned on the gas at the gas outlet, got the Bunsen burner out of the cabinet and lit it. To keep the clutter down, she threw the match into the garbage. She was wearing a loose, long sleeved sweater. She reached over the flame to get a bottle of chemical that she needed from the other side of the lab bench. Her sleeve caught on fire. She screamed for help. When no one responded, she ran out of the classroom with her sleeve ablaze. 30 Lighting a Bunsen Burner 1. Attach the burner hose to the gas outlet at the wall. 2. Close the air and gas valves on the burner. (Turn them clockwise as you look at them) 3. Light a match and open the gas outlet at the wall/table. 4. Open the gas valve on the burner until you hear a faint hissing sound of gas escaping. 5. Light the burner using matches or a lighter. 6. Adjust the air valve until you have a good inner cone and an outer cone about 5 cm high. Air Valve 7. Close the gas outlet (at the Wall/table) to extinguish the flame. Gas Valve A Bunsen burner is not a candle. NEVER blow it out. Gas Outlet The gas valve adjusts the height of the flame The air valve changes the color (temperature) of the flame 31 32 Alchemy Lab I. II. III. Problem: Can I change a penny into gold? Hypothesis: If alchemists are associated with turning metals into gold, then when I turn a penny to gold, I am an alchemist! Experiment: a. Materials: Bunsen burner 2 metal rings ring stand 150 mL beaker graduated cylinder spatula 250 mL beaker safety glasses steel wool 5 pennies (pre 1982) stirring rod wire gauze zinc (granulated) crucible tongs 3.0 M sodium hydroxide (NaOH) b. Procedure: 1. Set up a double ring stand to heat a 150 mL beaker. Make sure the beaker is steady on the ring stand/wire gauze and the second ring is around the middle of the beaker. The bottom ring/wire gauze should be about 5 cm above the Bunsen burner. 2. Using steel wool, buff your pennies. Keep one penny as a control for later comparisions. 3. Place a spatula tip full of zinc into the beaker. 4. Carefully pour 25.0 mL of 3.0 M sodium hydroxide (NaOH) into the same 150 mL beaker. Put the beaker on the ring stand. 5. Light the Bunsen burner. Using a blue flame, adjust the flame so the tip just touches the wire gauze. Bring the solution to “near” boiling. Lower the flame to maintain the solution at “just under” boiling. Move the Bunsen burner out from under the beaker if needed. DO NOT HEAT TO DRYNESS!! CAUTION: SODIUM HYDROXIDE IS DANGEROUS IF IT CONTACTS YOUR SKIN AND CAN CAUSE BLINDESS IF SPLASHED INTO EYES. THE FUMES ARE IRRITATING TO THE LUNGS AND WILL CAUSE COUGHING. THEREFORE – DO NOT BOIL – THERE SHOULD BE NO STEAM PRODUCED! 6. Using crucible tongs, carefully add no more than four pennies to the hot solution at one time. Do not drop the pennies into the solution. It could cause the beaker to break or cause the solution to splash out. Set the third penny aside as a control to compare to the treated coins. Carefully stir the solution with a stirring rod. Rotate the coins in the hot solution by using your crucible tongs. 33 7. Carefully stir the solution with a stirring rod. Rotate the coins in the hot solution by using the crucible tongs. 8. Make some observations about what is happening to the pennies in the beaker. 9. Fill a 250 mL beaker about half full with tap water. 10. With the crucible tongs, remove the pennies when they have completely turned to a silver color. Dip them into the beaker of water to rinse. Dry them in a paper towel. Set one aside for later comparisons. 11. Carefully move the Bunsen burner out from under the ring stand. 12. To turn the pennies to gold, gently heat them in the coolest part of the burner flame. Hold them vertically with the crucible tongs – DO NOT OVERHEAT! If the coins turn brown, you overheated them! 13. After the appearance of the coin has changed, place it in the beaker of water. Then remove, rinse, and dry it. 14. Record observations (in observation section) about changing the coin from silver to gold. 15. Clean up the equipment and work area. Return equipment to the proper location. IV. Observations: V. Conclusions: 34