Question 8
A diatomic gas ($$\gamma = 1.4$$) does 100 J of work in an isobaric expansion. The heat given to the gas is :
Solution
A diatomic gas ($$\gamma=1.4$$) does 100 J of work in isobaric expansion. To find the heat given, recall that at constant pressure $$Q = nC_p\Delta T$$ and $$W = nR\Delta T$$.
$$\frac{Q}{W}=\frac{C_p}{R}=\frac{\gamma R/(\gamma-1)}{R}=\frac{\gamma}{\gamma-1}=\frac{1.4}{0.4}=\frac{7}{2}=3.5$$
Therefore, $$Q=3.5\times W=3.5\times100=350$$ J.
The correct answer is Option (3): 350 J.
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