H2 and F2 react according to the following equation, forming HF.

Question

H2(g) + F2(g)  2HF(g); H° = –271 kJ
If H2(g) and F2(g) were mixed in a thermally insulated vessel, the reaction that occurred would be

a. endothermic, and the temperature of the reaction system would fall.
b. We could not tell unless the original and final temperatures were given.
c. exothermic, and the temperature of the reaction system would fall.
d. exothermic, and the temperature of the reaction system would rise.
e. endothermic, and the temperature of the reaction system would rise.

Answer 1

What do you not understand about this?
Exothermic means heat is given off by the system and the surrounding temperature rises.
Endothermic means heat is absorbed by the system and surroundings get cooler.

By convention, a negative sign for dH means that heat is released (given off) and a + sign for dH means heat is absorbed by the system (surroundings get cooler).

Answer 2

the Answer would that it is exothermic and the temperature of the reaction system would rise