Chapter 6, Problem 6.27QP

Hypothetical elements A₂ and B₂ react according to the following equation, forming the compound AB.

${\text{A}}_2(aq)+{\text{B}}_2(aq)\to 2\text{AB}(aq);\Delta H°=+271\text{ kJ}/\text{mol}$

If solutions A₂(aq) and B₂(aq), starting at the same temperature, are mixed in a coffee-cup calorimeter, the reaction that occurs is

1. a exothermic, and the temperature of the resulting solution rises.
2. b endothermic, and the temperature of the resulting solution rises.
3. c endothermic, and the temperature of the resulting solution falls.
4. d exothermic, and the temperature of the resulting solution falls.
5. e exothermic or endothermic, depending on the original and final temperatures.