Question

the $q_{rxn}$ is -90,100 j when 19.55 g k dissociates in water. what is the enthalpy of the reaction? $\delta h_{rxn} = ?$ kj/mol enter either a + or - sign and the magnitude.

Explanation:

Step1: Find moles of K

Molar mass of K is 39.10 g/mol. Moles of K = mass / molar mass = \( \frac{19.55\ g}{39.10\ g/mol} = 0.5\ mol \)

Step2: Calculate \( \Delta H_{rxn} \)

\( q_{rxn} = -90100\ J = -90.1\ kJ \) (since 1 kJ = 1000 J)
\( \Delta H_{rxn} = \frac{q_{rxn}}{\text{moles of K}} = \frac{-90.1\ kJ}{0.5\ mol} = -180.2\ kJ/mol \)

Answer:

-180.2