Question

$1kg$ of boiling water at $100^{\circ }C$ is dropped into Indian ocean, the temperature of which is $27^{\circ }C$. Calculate entropy change of the universe $\left(J{K}^{-1}\right)$
[specific heat of water $=4.2\times 10^{3}Jk{g}^{-1}$,
$\log \left(\frac{298}{373}\right)=0.0975]$

Answer 1

Answer: 108.15

Amount of heat lost by $1kg{H}_{2}O=ms\Delta T$
$=315000$ Joule
$\therefore$ This heat is absorbed by ocean hence entropy of ocean increases $=\frac{dq}{T}=1050J{K}^{-1}$
And entropy decrease of $1kg$ of boiled $H_{2}O$
$=-941.85J$
$\therefore \Delta S_{\text{universe }}=108.15J{K}^{-1}$