Rates of Reaction Questions (PDF)

1. According to collision theory, what two factors are necessary for a reaction to occur? a) High temperature and high pressure b) Collisions with suf cient energy and correct orientation c) A catalyst and high concentration d) Low activation energy and large surface area Answer: b) Collisions with...

1. According to collision theory, what two factors are necessary for a reaction to occur? a) High temperature and high pressure b) Collisions with suf cient energy and correct orientation c) A catalyst and high concentration d) Low activation energy and large surface area Answer: b) Collisions with suf cient energy and correct orientation 2. What is meant by the term "activation energy"? a) The total energy of the reactants. b) The energy released during a reaction. c) The minimum energy required for a reaction to occur. d) The energy difference between reactants and products. Answer: c) The minimum energy required for a reaction to occur. 3. What is the effect of increasing temperature on the rate of a reaction? a) Increases the rate. b) Decreases the rate. c) No effect. d) It depends on the reaction. Answer: a) Increases the rate. 4. What is the effect of increasing concentration on the rate of a reaction? a) Increases the rate. b) Decreases the rate. c) No effect. d) It depends on the reaction. Answer: a) Increases the rate. 5. What is the effect of increasing surface area on the rate of a reaction? a) Increases the rate. b) Decreases the rate. c) No effect. d) It depends on the reaction. Answer: a) Increases the rate. fi fi 6. What is the effect of adding a catalyst on the rate of a reaction? a) Increases the rate. b) Decreases the rate. c) No effect. d) It depends on the reaction. Answer: a) Increases the rate. 7. How does a catalyst increase the rate of a reaction? a) By increasing the temperature. b) By increasing the concentration of reactants. c) By providing an alternative reaction pathway with a lower activation energy. d) By increasing the surface area of reactants. Answer: c) By providing an alternative reaction pathway with a lower activation energy. 8. On a Maxwell-Boltzmann distribution curve, what does the area under the curve represent? a) The activation energy. b) The total number of particles. c) The average kinetic energy. d) The rate of reaction. Answer: b) The total number of particles. 9. On a Maxwell-Boltzmann distribution curve, what happens to the peak as temperature increases? a) The peak height increases and shifts to the left. b) The peak height decreases and shifts to the right. c) The peak height increases and shifts to the right. d) The peak height decreases and shifts to the left. Answer: b) The peak height decreases and shifts to the right. 10. Which of the following practical methods measures reaction rate by recording gas volume over time? a) Mass loss method b) Gas collection method c) Black cross method d) Colorimetry Answer: b) Gas collection method 11. Which of the following practical methods measures reaction rate by recording mass loss over time? a) Mass loss method b) Gas collection method c) Black cross method d) Colorimetry Answer: a) Mass loss method 12. In the "black cross" experiment, what substance obscures the cross? a) Sodium chloride (NaCl) b) Water (H₂O) c) Sulfur dioxide (SO₂) d) Solid sulfur (S) Answer: d) Solid sulfur (S) 13. What is the "black cross" experiment suitable to nd the reaction rate for? a) Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g) b) HCl(aq) + Na₂S₂O₃(aq) → 2NaCl(aq) + S(s) + H₂O(l) + SO₂(g) c) CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(aq) + CO₂(g) fi  User con nue ti WJEC Okay, let's continue providing the multiple-choice answer options: 13. What is the "black cross" experiment suitable to nd the reaction rate for? a) Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g) b) HCl(aq) + Na₂S₂O₃(aq) → 2NaCl(aq) + S(s) + H₂O(l) + SO₂(g) c) CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(aq) + CO₂(g) d) 2H₂O₂(aq) → 2H₂O(l) + O₂(g) Answer: b) HCl(aq) + Na₂S₂O₃(aq) → 2NaCl(aq) + S(s) + H₂O(l) + SO₂(g) 14. What piece of apparatus is usually used to measure the volume of gas produced in a reaction? a) Burette b) Pipette c) Gas syringe d) Conical ask fl fi Answer: c) Gas syringe 15. In the "iodine clock" reaction, what substance is used to delay the color change? a) Iodide ions (I⁻) b) Starch c) Thiosulfate (S₂O₃²⁻) d) Hydrogen peroxide (H₂O₂) Answer: c) Thiosulfate (S₂O₃²⁻) 16. In the "iodine clock" reaction, what is the color change observed? a) Colorless to red b) Red to colorless c) Colorless to blue-black d) Blue-black to colorless Answer: c) Colorless to blue-black 17. What technique can be used to monitor reactions that have a colour change? a) Titration b) Gas collection c) Mass loss d) Colorimetry Answer: d) Colorimetry 18. How is a calibration curve used in colorimetry? a) To measure the volume of reactants. b) To measure the mass of products. c) To convert absorbance readings to concentration. d) To measure the rate of reaction directly. Answer: c) To convert absorbance readings to concentration. 19. In the reaction: Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g), which practical method would be *most* suitable for measuring the rate? a) Mass loss method b) Gas collection method c) Black cross method d) Titration Answer: b) Gas collection method 20. In the reaction: CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g), which practical method would be *most* suitable for measuring the rate? a) Mass loss method b) Gas collection method c) Black cross method d) Colorimetry Answer: a) Mass loss method 21. A Maxwell-Boltzmann distribution shifts to the right. What caused this to happen? a) A decrease in temperature b) An increase in temperature c) An increase in concentration d) Addition of a catalyst Answer: b) An increase in temperature 22. Which equation is the "black cross" method used to investigate? a) Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g) b) HCl(aq) + Na₂S₂O₃(aq) → 2NaCl(aq) + S(s) + H₂O(l) + SO₂(g) c) CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g) d) 2H₂O₂(aq) → 2H₂O(l) + O₂(g) Answer: b) HCl(aq) + Na₂S₂O₃(aq) → 2NaCl(aq) + S(s) + H₂O(l) + SO₂(g) 23. What is the role of Fe in the production of ammonia? a) Reactant b) Product c) Catalyst d) Intermediate Answer: c) Catalyst 24. What is the equation for the production of ammonia? a) N₂(g) + H₂(g) → NH₃(g) b) N₂(g) + 2H₂(g) → 2NH₃(g) c) N₂(g) + 3H₂(g) → 2NH₃(g) d) 2N₂(g) + 3H₂(g) → 2NH₃(g) Answer: c) N₂(g) + 3H₂(g) → 2NH₃(g) 25. On a reaction pro le, how is the activation energy represented? a) The difference in energy from the reactants to the products. b) The difference in energy from the reactants to the top of the curve. c) The total energy of the products. d) The total area under the curve. Answer: b) The difference in energy from the reactants to the top of the curve. fi