MCQ
$36\, mL$ of pure water takes $100\, sec$ to evaporate from a vessel and heater connected to an electric source which delivers $806\, watt$. The $\Delta H_{vaporization}$ of $H_2O$ is.....$ kJ/mol$
  • $40.3$
  • B
    $43.2$
  • C
    $4.03$
  • D
    None of these

Answer

Correct option: A.
$40.3$
a
$1$ $watt$ $=1 \,\mathrm{J} / \mathrm{sec}$

Total heat supplied for $36\, \mathrm{mL}\, \mathrm{H}_{2} \mathrm{O}$

$=806 \times 100$

$=80600\, \mathrm{J}$

$\Delta \mathrm{H}_{\mathrm{vap}} =\frac{80600}{36} \times 18$

$=40300 \,\mathrm{J} \text { or } 40.3\, \mathrm{kJ} / \mathrm{mol}$

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