Senior High School Physical Science Quarter 1 – Module 8: Collision Theory 1 For the learner: Welcome to the Physical Science module on Collision Theory. This module was created to aid you with your studies, particularly during this pandemic when face-to-face communication is not possible. All of the materials for the activities can be found in your homes, making them simple to complete. It is expected of you to have fun while learning. The following components and icons are included in this module: What I Need to Know This will offer you a general overview of the skills or competencies you should learn in the module. What I Know This section offers an activity that will test your knowledge of the upcoming lesson. You may choose to skip this module if you get all of the answers correct (100%). What’s In This is a quick drill or refresher to help you connect the current and previous lessons. What’s New The new lesson will be introduced to you in this section in a variety of ways, including a narrative, a song, a poem, a problem opener, an activity, or a circumstance. What is It A brief discussion of the lesson is provided in this section. This is designed to assist you in learning new concepts and skills. What’s More This section contains tasks for individual practice to help you solidify your knowledge and abilities on the subject. 2 What I Have Learned This may include fill-in-the-blank questions or blank sentences/paragraphs to help you absorb what you learned in the class. What I Can Do This section has an activity that will assist you in applying your new knowledge or skill to real-world problems or issues. Assessment This task is designed to assess your mastery of the learning competency. Additional Activities Another activity will be offered to you in this section to help you expand your knowledge or skill of the lesson you just studied. Answer Key This contains answers to all activities in the module. At the end of this module you will also find: References This is a list of all sources used in developing this module. The following are some reminders in using this module: 1. Use the module with care. 2. Don’t forget to answer “What I Know” before moving on to the other activities included in the module. 3. Read the instruction carefully before doing each task. 4. Observe honesty and integrity in doing the tasks and checking your answers. 5. Finish the task at hand before proceeding to the next. 6. If you encounter difficulty in answering this module, do not hesitate to ask your teacher. 3 What I Need to Know This module is created and written is to assist learners in recognizing how Collision Theory affects the chemical reaction rate. Collision theory explains chemical reactions and their rates in a qualitative manner. The key principle of collision theory is that molecules must collide to react. This basic rule guides any analysis of an ordinary mechanism of reaction. The scope of this learning material covers many different learning situations where learners could relate their personal experiences. The language used recognizes the diverse vocabulary level of learners. The lessons are organized following the regular order of the course. Learning Competency: • The learners: use simple collision theory to explain the effects of concentration, temperature, and particle size on the rate of reaction S11/12PS-IIIf-23 Specifically, the lesson objectives are: 1. describe collision theory; 2. explain the effects of concentration, temperature, and particle size on the rate of reaction; and 3. relate collision theory with everyday life experience. What I Know Direction: Read each statement carefully. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. What is collision theory? a. Molecules must collide in the correct orientation with enough energy to bond. b. Molecules need enough energy to collide and react. c. Atoms constantly collide and react. d. The minimum energy needed for atoms to react. 2. What is the rate of reaction? a. How much energy is needed for a reaction to occur. b. The energy required to break a bond. c. The time it takes for a reaction to occur. d. Collision Theory 3. What factors affect the rate of reaction? a. Temperature, Concentration, Pressure, and Energy b. Surface Area, Concentration, Energy, and Pressure c. Temperature, Catalyst, Concentration, and Surface area 4 d. Pressure, Surface area, Density and Energy 4. Increasing the temperature of your solution will _____. a. not affect the rate of reaction. b. speeds up the rate of reaction. c. slows down the rate of reaction. d. either speeds up or slows down the rate of reaction. 5. Decreasing the concentration of a substance will _______. a. slows down the reaction. b. speeds up the reaction. c. does not affect the reaction. d. either speeds up or slows down the rate of reaction. 6. Which has more surface area? a. large chunks of chalk b. cube of sugar c. powdered sugar d. small chunks of sugar 7. If you shrink the container size that your gas substance is in, what will happen? a. The reaction rate will stay the same b. The reaction rate will speed up c. The reaction rate will slow down d. either speed up or slow down the rate of reaction 8. More collisions correspond to a: a. faster reaction rate b. slower reaction rate c. constant reaction rate d. none of the above 9. What criteria must be met for reactant collisions to result in a successful product? a. The reactants must collide with each other b. The reactants must collide with enough energy and be in the right positions c. The reactants must have enough energy to form the activated complex d. none of the above 10. What is a catalyst? a. Something added to a reaction to slow it down b. Something added to a reaction to speed it up c. Something added to a reaction to increase the surface area d. Something added to a reaction to change its concentration 11. Which is/are factor/s that would affect the rate of a reaction? a. temperature b. adding a catalyst c. concentration d. all of the choices 12. If I wanted to create more space for particles to collide, I would ____. a. raise the pressure b. raise the temperature c. increase the concentration d. increase the surface area 13. Which of the following would NOT increase the rate of reaction? a. increasing the temperature 5 b. increasing the surface area c. increasing the volume d. increasing the concentrations 14. As the temperature of a reaction is increased, the rate of the reaction increases because the __________. a. reactant molecules collide less frequently b. reactant molecules collide more frequently and with greater energy per collision c. activation energy is lowered d. reactant molecules collide less frequently and with greater energy per collision 15. The rate of a reaction depends on __________. a. collision frequency c. collision orientation b. collision energy d. all of the choices What’s In We encounter chemical reactions everywhere. A substance changes in the presence of another substance or even by itself. Because there are tens of millions of known substances, there are a huge number of possible chemical reactions. We see them every day like combustion, photosynthesis, aerobic cellular respiration, anaerobic respiration (including fermentation), oxidation (including rust), digestion, and many more. A chemical reaction is a process in which one or more substances, also called reactants, are converted to one or more different substances, known as products. Chemical reactions occur at various speeds. Reactions might happen quite quickly like striking a match and burning of petrol in the car engine, or slowly like for example rusting of iron or fermentation of sugar into ethyl alcohol and carbon dioxide can take place in several hours or even in several days. Have you ever wondered why a chemical reaction happens? What elements are required for a chemical reaction to take place? In this lesson, learners will describe collision theory, which is used to predict the rates of chemical reactions. Learners will determine the different factors that affect the rate of reaction. 6 What’s New Activity 1. Reaction Rates: When Surface Area Matters! I. Objective: To investigate the effect of particle size on the rate of a reaction. II. Materials: vinegar – 100 mL chalk – 2 small pieces (same size) 2 similar cups a mortar and pestle stopwatch III. Procedure: 1. Grind 1 piece of chalk using a mortar and pestle (put the powdered chalk in a cup) 2. Leave the 2nd piece of chalk whole (put the chalk in a cup) 3. Prepare a stopwatch to time the reactions. 4. Add 100 mL of vinegar to the ground chalk. 5. Observe the reaction and record observations. 6. Time the reaction and record. 7. Add 100 mL to the entire piece of chalk 8. Observe the reaction and record observations 9. Time the reaction and record your observations in Table 1. IV. Results: Table 1: The Effect of Surface Area/ Particle Size on Reaction Rates Material Time the tablet was fully Observations dissolved Whole chalk Powdered chalk Guide Questions: 1. Which piece of chalk produced a faster reaction? Why? _________________________________________________________________ ___________________________________________________________ 3. Explain the effects of particle size on the rate of reaction. _________________________________________________________________ _______________________________________________________________ 7 V. Conclusion: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Activity 2. The Effect of Concentration on Reaction Rates I. Objective: Investigate the effect of concentration on the rate of a reaction. II. Materials: 3 clear drinking glasses baking soda vinegar spoon III. Procedure: 1. Prepare 3 drinking glasses. 1. Dilute vinegar in water to get three different concentrations. The ratio of water to vinegar 0:1 (pure vinegar), 1:1, and 2:1. (make sure to have a total of 100 ml for each solution. 2. Quickly add 1 tbsp. of baking soda to each concentration and stir. Note the difference in reactions. 3. Record your observations. IV. Results: Table 2: The Effect of Concentration on Reaction Rates Materials Observations Vinegar 0:1 Vinegar 1:1 Vinegar 2:1 Guide Questions: 1. Which glass has the most amount of bubbles formed? Why? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 3. Explain the effects of concentration on the rate of reaction. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 8 V. Conclusion: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Activity 3: The Effect of Temperature on Reaction Rates I. Objective: Investigate the effect of temperature on the rate of a reaction. II. Materials: 3 clear drinking glasses brown sugar spoon hot water tap water (room temperature) cold water ice (optional) III. Procedure: 1. Prepare 3 drinking glasses 2. Fill the first glass with 100 ml hot water, fill the second glass with 100 ml tap water, and fill the third glass with 100 ml cold water (you may add ice if you like). 3. In each glass, put 1 tbsp. of brown sugar. 4. Stir each glass 10 times using the spoon. 5. Observe what happen to the sugar at the bottom of each glass. 6. Record your observations in Table 3. IV. Results: Table 3. The Effect of Temperature on Reaction Rates Materials Observations hot water tap water cold water Guide Questions: 1. Which glass has the least amount of sugar at the bottom of the glass? Why? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 3. Explain the effects of temperature on the rate of reaction. _________________________________________________________________ 9 _________________________________________________________________ _________________________________________________________________ V. Conclusion: _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Activity 4: The Effect of Catalyst on Reaction Rates I. Objective: Investigate the effect of catalyst on the rate of a reaction. II. Materials: 2 clear drinking glasses hydrogen peroxide spoon yeast III. Procedure: 1. Prepare 2 clear drinking glasses 2. Fill each glass with 25 ml Hydrogen peroxide. 3. Put ½ tsp of yeast in the first glass, then just let the second glass be as it is. 4. Observe which glass will produce more bubbles. 6. Record your observations. IV. Results: Table 4. The Effect of Catalyst on Reaction Rates Materials Hydrogen peroxide Hydrogen peroxide with yeast Observations Guide Questions: 1. Which glass has produced more bubbles? Why? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 3. Explain the effects of catalyst on the rate of reaction. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ V. Conclusion: _________________________________________________________________ _________________________________________________________________ 10 _________________________________________________________________ _________________________________________________________________ What is It Collision Theory: How Chemical Reactions Occur Collision theory states that for a chemical reaction to take place, the reacting particles must collide. The rate of the reaction depends on the frequency of collisions. The theory also tells us that reacting particles often collide without reacting. The kinetic energy required to break the necessary bonds and make new bonds is provided by the collision of molecules in a chemical process. Even when there is a collision, not all collisions are successful. For collisions to be effective collisions, particles must possess the minimum amount of energy needed for the reaction and must collide with proper orientation. This energy, used to initiate the reaction, is called the activation energy. The activation energy of a chemical reaction is closely related to its rate. Specifically, the higher the activation energy, the slower the chemical reaction will be. This is because molecules can only complete the reaction once they have reached the top of the activation energy barrier. Factors that Affect Reaction Rates The collision theory is used to explain the factors that affect the reaction rate. The four main factors that affect reaction rate are particle size (surface area) of the reactants, the concentration of the reactants, temperature, and the presence of catalysts. Let us explore these factors that affect the reaction rate. Effect of Surface Area on Reaction Rate: In Activity 1, we used whole chalk and powdered chalk to compare the rates of reaction. You observed that the powdered chalk dissolves faster in a cup of water than the whole chalk. This happened because while they have the same mass, they differ in surface area. Breaking the chalk into smaller pieces increases its surface area allowing more particles to be available for a collision. In collision theory, the solid is divided into smaller pieces, then there is a greater surface area; therefore, more particles can react, and the reaction rate increases. 11 Figure 1: Surface area of solid Any reaction involving a solid can only occur at the solid's surface. The surface area of solid increases as it is divided into several pieces. This means that the reactant particles will collide with a larger surface area. The smaller the pieces, the larger the surface area. This suggests that there will be more collisions and a higher possibility of a reaction. Remember! If the surface area of a reactant is increased: • more particles are exposed to the other reactant • there are more collisions • the rate of reaction increases Effect of Concentration on Reaction Rate: In Activity 2, we used 3 concentrations of vinegar were used. Pure vinegar has the most produced bubbles while the least concentrated vinegar has the least produced bubbles. Figure 2: Concentration of molecules 12 An increase in the concentration of reactants increases the reaction rate. At higher concentrations, the molecules of the reactants are closer to each other; therefore, collisions occur more frequently, a higher percentage of collisions are effective, and the reaction rate increases. Remember! • • • increasing the concentration of a reactant, there will be more of the chemical present. more reactant particles moving together allow more collisions to happen, so the reaction rate is increased. the higher the concentration of reactants, the faster the rate of a reaction will be. Effect of Temperature on Reaction Rate: In Activity 3, we filled 3 drinking glasses with 3 different temperatures of water then added an equal amount of brown sugar to each glass. We observed that an increase in the temperature of reactants usually increases the reaction rate. At higher temperatures, the molecules of the reactants move faster; therefore, collisions occur more frequently, a higher percentage of collisions are effective, and the reaction rate increases. A general rule of thumb is that on average, the reaction rate doubles for every 10°C rise in temperature. Remember! • • • Reactants must be moving fast enough and hit each other hard enough for a chemical reaction to take place. Increasing the temperature increases the average speed of the reactant molecules. As more molecules move faster, the number of molecules moving fast enough to react increases, which results in the faster formation of products. Effect of a Catalyst on Reaction Rate: In Activity 4, we prepared 2 glasses with 25 ml of hydrogen peroxide. Then we added ½ tsp. to 1 glass then let the other glass stay as it is. We observed that more bubbles were produced with the presence of yeast. This is because the yeast acts as a catalyst for the decomposition of hydrogen peroxide into hydrogen gas and oxygen gas. A catalyst is a substance that changes the reaction rate without being consumed by the reaction. A catalyst acts by lowering the activation energy required for a reaction to take place, thus allowing the reaction to occur more rapidly. (This will be discussed more in the next module). 13 What’s More Activity 5. Increase-Decrease! Complete the following table by indicating whether each of the following scenarios would either increase or decrease the rate of reaction. Scenario Effect on Chemical Reaction Rate removing heat diluting a solution decreasing surface area adding a catalyst increasing temperature Activity 6. What is it! Direction: Complete the table by indicating which factor would have the greatest impact on the rate of reaction of these real-life situations. Scenario Factors that Effect Chemical Reaction Rate 1. cooking small slices of meat 2. exhaust from car engine passes through a converter changing poisonous nitrogen oxides into nitrogen gas and oxygen gas 3. storing milk in the refrigerator 4. salt dissolves fast in hot water 5. Tearing paper into small pieces 6. leaving fresh fish on top of a table 7. fruits and vegetables ripen faster in the summer than during rainy days 8. two antacid tablets will neutralize a given amount of acid faster than one tablet will 9. smaller pieces of charcoal are used to cook food faster 10. industries break down pulp to produce sanitary paper 14 What I Have Learned Sentence Completion. Complete each statement with a word/ concept in the blank of the item. 1. A freshly exposed surface of metallic sodium tarnishes almost instantly if exposed to air and moisture, while iron will slowly turn to rust under the same conditions. In these two situations, the__________________ refers to how quickly or slowly reactants turn into products. 2. Adding _________________________ will increase the rate of reaction because this causes the particles of the reactants to move more quickly, resulting in more collisions and more ______________________. 3. Removing heat will lower the ____________________, causing the particles of the reactants to slow down, resulting in less frequent collisions. 4. ___________________ refers to how much solute is dissolved in a solution. If there is a greater concentration of reactant particles present, there is a greater chance that __________________ among them will occur. More collisions mean a higher rate of reaction. 5. A concentrated acid solution will react more quickly than a _______________ acid solution because there are more molecules present, increasing the chance of collisions. 6. Grains of sugar have a greater ______________________ than a solid cube of sugar of the same mass, and therefore will dissolve quicker in water. 7. A ______________ therefore speeds up a reaction but remains unchanged after the reaction is complete. 8. _____________________ states that for a chemical reaction to occur, the reacting particles must collide with one another. 9. If a reaction has a low rate, that means the molecules combine at a _________speed than a reaction with a high rate. 10. A chemical reaction between two or more substances requires close _________ between the reactants. 15 What I Can Do YOU GOT THIS! Direction: Choose from one of the factors that affect the rate of chemical reaction (surface area, temperature, concentration, and catalyst). Give a real-life example of what you have chosen. Explain why it can affect the rate of reaction. Then take a photo of your example and attach it below. __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ Assessment Direction: Read each statement carefully. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. What factors affect the rate of reaction? a. Temperature, Concentration, Pressure, and Energy b. Surface Area, Concentration, Energy, and Pressure c. Temperature, Catalyst, Concentration, and Surface area d. Pressure, Surface area, Density and Energy 2. Increasing the temperature of your solution will _____. a. not affect the rate of reaction. b. speed up the rate of reaction. c. slows down the rate of reaction. d. either speeds up or slows down the rate of reaction. 3. Which has more surface area? a. large chunks of chalk b. cube of sugar c. powdered sugar d. small chunks of sugar 4. As the temperature of a reaction is increased, the rate of the reaction increases because the __________. a. reactant molecules collide less frequently b. reactant molecules collide more frequently and with greater energy per collision 16 c. activation energy is lowered d. reactant molecules collide less frequently and with greater energy per collision 5. If you shrink the container size that your gas substance is in what will happen? a. The reaction rate will stay the same b. The reaction rate will speed up c. The reaction rate will slow down d. either speed up or slow down the rate of reaction 6. What is collision theory? a. Molecules must collide in the correct orientation with enough energy to bond. b. Molecules need enough energy to collide and react. c. Atoms constantly collide and react. d. The minimum energy needed for atoms to react. 7. More collisions correspond to a: a. faster reaction rate b. slower reaction rate c. constant reaction rate d. none of the above 8. What is a catalyst? a. Something added to a reaction to slow it down b. Something added to a reaction to speed it up c. Something added to a reaction to increase the surface area d. Something added to a reaction to change its concentration 9. Decreasing the concentration of a substance will _______. a. slows down the reaction. b. speeds up the reaction. c. has no effect on the reaction. d. either speeds up or slows down the rate of reaction. 10. Which is/are factor/s that would affect the rate of a reaction? a. temperature b. adding a catalyst c. concentration d. all of the choices 11. What is the rate of reaction? a. How much energy is needed for a reaction to occur. b. The energy required to break a bond. c. The time it takes for a reaction to occur. d. Collision Theory 12. Which of the following would NOT increase the rate of reaction? a. increasing the temperature b. increasing the surface area c. increasing the volume d. increasing the concentrations 13. The rate of a reaction depends on __________. a. collision frequency c. collision orientation b. collision energy d. all of the choices 14. If I wanted to create more space for particles to collide, I would ____. 17 a. add catalyst b. raise the temperature c. increase the concentration d. increase the surface area 15. What criteria must be met for reactant collisions to result in a successful product? a. The reactants must collide with each other b. The reactants must collide with enough energy and be in the right positions c. The reactants must have enough energy to form the activated complex d. none of the above WORD MATCH! Direction: Draw a line from each word in column A to its description in column B. A 1. catalyst 2. concentration 3. surface area 4. temperature 5. collision theory B a. It is the measure of how much of a given substance there is mixed with another substance. b. It is the degree or intensity of heat present in a substance or object. c. For a collision to be successful, reacting particles must collide with sufficient energy, and with the proper orientation. d. It is a measure of the total area that the surface of the object occupies. e. It is a substance that increases the rate of a chemical reaction without itself undergoing any chemical change. 18 Answer Key REFERENCES Reyes, J. A. C., & Reyes, M. A. C. (2017). Physical Science. JIMCZYVILLE Publications. Sabibio, M. B., & David, O. M. (2019). Physical Science (2nd ed.). DIWA Learning Systems Inc. Ungson, O. B., & Teofe, F. T. (2016). Physical Science. Trinitas Publishing Inc. Wilson, J. D., Higgins Jr., C. A., & Torres, O. (2016). An Introduction to Physical Science (14th ed.). Rex Book Store Inc. 19