Question

if an experiment has a $q_{rxn}$ of 518.07 j, calculate the change in enthalpy of the reaction if there were 0.04 mol of product in the solution.
7.72 kj/mol
-12.95 kj/mol
-12951.75 kj/mol
12.95 kj/mol

Explanation:

Step1: Convert \( q_{rxn} \) from J to kJ

Since \( 1\ kJ = 1000\ J \), then \( q_{rxn}=518.07\ J=\frac{518.07}{1000}\ kJ = 0.51807\ kJ \)

Step2: Calculate \( \Delta H \) (change in enthalpy)

The formula for molar enthalpy change is \( \Delta H=\frac{q_{rxn}}{n} \), where \( n = 0.04\ mol \) (amount of product).
Substitute the values: \( \Delta H=\frac{0.51807\ kJ}{0.04\ mol}=12.95175\ kJ/mol\approx12.95\ kJ/mol \)

Answer:

12.95 kJ/mol