MCAT General Chemistry Question 90: Answer and Explanation
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Question: 90
15. Which of the following statements best describes the effect of lowering the temperature of the following reaction?
- A. [C] and [D] would increase.
- B. [A] and [B] would increase.
- C. ΔH would increase.
- D. ΔH would decrease.
Correct Answer: A
Explanation:
A negative ΔH value indicates an exothermic reaction, meaning that the forward reaction produces heat. Visualize this as follows:
A + B - C + D + heat
This means that removing heat by decreasing the temperature is similar to removing any other product of the reaction. To compensate for this loss, the reaction will shift to the right, causing an increase in the concentrations of C and D as well as a decrease in the concentrations of A and B.