Question

the molar heat of fusion of gold is 12.550 kj mol⁻¹. at its melting point, how much mass of melted gold must solidify to release 235.0 kj of energy? use q = nδh. 222.5 g 18.73 g 2,949.3 g 3,688.3 g

Explanation:

Step1: Calculate the number of moles

We know that $q = n\Delta H$. Rearranging for $n$, we get $n=\frac{q}{\Delta H}$. Given $q = 235.0\ kJ$ and $\Delta H=12.550\ kJ/mol$, so $n=\frac{235.0\ kJ}{12.550\ kJ/mol}=18.725\ mol$.

Step2: Calculate the mass

The molar mass of gold ($Au$) is $M = 196.97\ g/mol$. Using the formula $m=n\times M$, we have $m = 18.725\ mol\times196.97\ g/mol\approx3688.3\ g$.

Answer:

$3,688.3\ g$