Question

question 8 of 20
the heat of vaporization for ethanol is 0.826 kj/g. calculate the heat energy in joules required to boil 78.75 g of ethanol.
heat energy: j

Explanation:

Step1: Identify the formula

The formula for heat energy $Q$ is $Q = m\times\Delta H_{vap}$, where $m$ is the mass and $\Delta H_{vap}$ is the heat of vaporization.

Step2: Convert kJ to J

Since $1\ kJ= 1000\ J$, the heat of vaporization $\Delta H_{vap}=0.826\ kJ/g = 0.826\times1000\ J/g=826\ J/g$.

Step3: Calculate the heat energy

$m = 78.75\ g$, $\Delta H_{vap}=826\ J/g$. Then $Q=m\times\Delta H_{vap}=78.75\times826$.
$Q = 78.75\times826=65047.5\ J$.

Answer:

$65047.5$