Question

$36mL$ of pure water takes $100sec$ to evaporate from a vessel and heater connected to an electric source which delivers $806watt$. The $\Delta H_{vaporization}$ of $H_{2}O$ is

• A. $40.3kJmo{l}^{-1}$
• B. $43.2kJmo{l}^{-1}$
• C. $4.03kJmo{l}^{-1}$
• D. None of these

Answer 1

The correct option is A $40.3kJmo{l}^{-1}$

$1watt=1Jse{c}^{-1}\text{Total heat supplied for 36 mL}{H}_{2}O=806\times 100=80600J\Delta H_{vap}=\frac{80600}{36}\times 18=40300Jor40.3kJmo{l}^{-1}$