Thermodynamics - Result Question 2
2. A sample of $0.1 g$ of water at $100^{\circ} C$ and normal pressure $(1.013 \times 10^{5} Nm^{-2})$ requires $54 cal$ of heat energy to convert to steam at $100^{\circ} C$. If the volume of the steam produced is $167.1 cc$, the change in internal energy of the sample, is
[2019]
(a) $104.3 J$
(b) $208.7 J$
(c) $84.5 J$
(d) $42.2 J$
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Answer:
Correct Answer: 2. (b)
Solution:
- (b) Using first law of thermodynamics equation, $\Delta Q=\Delta U+\Delta W$
$\Rightarrow 54 \times 4.18$ $=\Delta U+1.013 \times 10^{5}(167.1 \times 10^{-6}-0)$
$\Rightarrow \Delta U=208.7 J$
