Question

Determine the value for the following reaction.

N2(g) + 3H2(g) → 2NH3(g)+ 22,000 cal
ΔH = _____
22,000 kcal
-22,000 kcal
22 kcal
-22 kcal

Answer 1

ΔH = -22 kcal

Step-by-step explanation:

N₂(g) + 3H₂(g) ⇌ 2NH₃(g) + 22 000 cal

Energy is on the right-hand side of the equation, so it is being released by the system.

The thermodynamic convention is that energy going out of a system is negative. Thus,

ΔH = -22 000 cal Convert to kilocalories

ΔH = -22 kcal

A and B are both wrong, because you divide by 1000 to convert calories to kilocalories.

C is wrong, because the sign must be negative for an exothermic reaction.