Question 6.4: Calculating the Heat of Reaction from the Stoichiometry How ...

General Chemistry

Calculating the Heat of Reaction from the Stoichiometry

How much heat is evolved when $9.07 \times 10^5$ g of ammonia is produced according to the following equation? (Assume that the reaction occurs at constant pressure.)

N_2(g) + 3H_2(g) \to 2NH_3(g); ΔH = -91.8 kJ

PROBLEM STRATEGY

The calculation involves converting grams of $NH_3$ to moles of $NH_3$ and then to kilojoules of heat.

Grams of $NH_3$ → moles of $NH_3$ → kilojoules of heat

You obtain the conversion factor for the second step from the thermochemical equation, which says that the production of 2 mol $NH_3$ is accompanied by $q_p$ = -91.8 kJ.

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