Rate of Reaction Quiz
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5 questions, one answer each
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1. Which of the following statements about catalysts is correct?
- A. A catalyst is used up in a reaction and must be replaced
- B. A catalyst increases the rate of reaction and remains unchanged at the end
- C. A catalyst lowers the temperature of a reaction to slow it down
- D. A catalyst changes the products formed in a chemical reaction
2. A student investigates the rate of reaction between hydrochloric acid and calcium carbonate powder by measuring the change in mass over time. Why is measuring change in mass a suitable method for this experiment?
- A. It measures the volume of the solid reactant that dissolves
- B. Carbon dioxide gas is produced and escapes, causing a measurable decrease in mass
- C. It directly measures the concentration of the acid solution
- D. It allows the student to see a colour change in the reaction mixture
3. Using collision theory, explain why increasing the concentration of a solution increases the rate of reaction.
- A. Higher concentration increases the temperature of the solution
- B. Higher concentration increases the number of particles per unit volume, leading to more frequent collisions
- C. Higher concentration decreases the activation energy of the reaction
- D. Higher concentration causes the particles to move more slowly and collide with more force
4. A student performs two experiments investigating the reaction between zinc and dilute sulfuric acid. In experiment 1, zinc powder is used. In experiment 2, a zinc block of equal mass is used. Both are at the same temperature and acid concentration. Which statement correctly explains the difference in reaction rates?
- A. The zinc powder reacts faster because it has a larger surface area exposed to the acid, increasing collision frequency with acid particles
- B. The zinc block reacts faster because larger pieces have more kinetic energy
- C. Both react at the same rate because they have equal mass and are at the same temperature
- D. The zinc powder reacts faster because the smaller particles have lower activation energy
5. A catalyst works by decreasing the activation energy of a reaction. Using collision theory, why does lowering the activation energy result in an increased rate of reaction?
- A. A lower activation energy means more particles now have sufficient kinetic energy to react when they collide, so a greater fraction of collisions are effective
- B. A lower activation energy increases the temperature of the reaction mixture
- C. A lower activation energy reduces the number of collisions that occur
- D. A lower activation energy causes particles to move faster and collide more frequently