Collision Theory Gizmo Rate of Reactions

Name: KEY Collision Theory Gizmo Rate of Reactions A chemical reaction causes the chemical compositions of substances to change. Reactants are substances that enter into a reaction, and products are substances produced by the reaction. The Collision Theory Gizmo™ allows you to experiment with several factors that affect the rate at which reactants are transformed into products in a chemical reaction. In this activity, you will simulate chemical reactions and manipulate various variables to determine the time for the reactions to fully occur. Settings Time Taken for Reaction (min:sec) Reason for why it is different than the standard Standard Reactant 1 mol/L Catalyst 0 mol/L Surface Area – Minimum Temperature 100 °C 25:12 Increase Concentration Reactant 2.0 mol/L Catalyst 0 mol/L Surface Area – Minimum Temperature 100 °C 5:14 There are more reactant molecules in a given volume (and a small amount of space) will make them bump into each other more often. 149.17 There are less reactant molecules in a given volume and they are not likely to bump into each other. 4:52 A catalyst helps bring reactants together in the correct orientation so they can form a bond (lowers the activation energy needed to do this). 4:46 The reactants are more exposed to other reactants and can bump into each other easily. 4:23 The reactants move very quickly and bump into each other often and with enough energy. 154:13 The reactants move very slowly and rarely bump into each other with enough energy. Decrease Concentration Reactant 0.5 mol/L Catalyst 0 mol/L Surface Area – Minimum Temperature 100 °C Addition of a Catalyst Reactant 1 mol/L Catalyst 0.25 mol/L Surface Area – Minimum Temperature 100 °C Increase in Surface Area Reactant 1 mol/L Catalyst 0 mol/L Surface Area – Maximum Temperature 100 °C Increase in Temperature Reactant 1 mol/L Catalyst 0 mol/L Surface Area – Minimum Temperature 200 °C Decrease in Temperature Reactant 1 mol/L Catalyst 0 mol/L Surface Area – Minimum Temperature 50 °C Apply your results: 1. For two molecules to react, they must collide at just the right angle and with enough energy to break the original bonds and form new ones. Based on these facts, why does the reaction tend to go more quickly at higher temperatures? The reactants move very quickly and bump into each other often and with enough energy. At a lower temperature, they are much slower. 2. a. Why does the reaction proceed more quickly when the surface area is increased? The reactants are more exposed to other reactants and can bump into each other easily. b. What would happen if the substance was covered and the surface area was decreased? Why is this? The reactants would be prevented from bumping into each other and could not form a bond if one of the substances was covered. This would inhibit (stop) the reaction or severely slow it down. 3. Most of the chemical reactions inside your body rely on protein catalysts called enzymes to take place. For example, the enzyme pepsin helps to break down protein molecules in your stomach. What might happen if your stomach stopped producing pepsin? -Your stomach may not be able to break down all food molecules -Your digestion would be slowed down 4. Hydrochloric acid reacts with the mineral calcite to produce carbon dioxide gas, water, and calcium chloride. Based on what you have learned in the gizmo, what are three things you could do to make the reaction occur more quickly and why would they work? -heat up acid (increases speed of reactants and increases collisions) -break up the calcite (increases surface area and causes more collisions) -Add a catalyst (will help reactants come together) -Use a concentrated acid (increases reactants that are close together and can bump into each other).