Answer
597 g
Work Step by Step
Number of moles of ethanol that can be vaporized=
$\frac{q}{\Delta_{vap}H}=\frac{500.\,kJ}{38.6\,kJ/mol}=12.95\,mol$
Mass in grams of ethanol= number of moles$\times$molar mass
$=12.95\,mol\times 46.07\,g/mol$
$=597\,g$
