Question

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of $37.0^{{}^{\circ }}\text{C}$ . As it does so, it absorbs 208 J of heat. The values of q and w for the process will be
(R = 8.314 J/mol K) (ln7.5 = 2.01)

• A. $\text{q}=-208\text{J}\text{,}\text{w }=+208\text{J}$
• B. $\text{q}=+208\text{J}\text{,}\text{w}=+208\text{J}$
• C. $\text{q}=+208\text{J}\text{,}\text{w}=-208\text{J}$
• D. $\text{q}=-208\text{J}\text{,}\text{w}=-208\text{J}$

Answer 1

Answer: (C)

Since, temperature remains constant, the process will be isothermal by nature.
For Isothermal reversible expansion:
$\Delta \text{E}=0=\text{q}+\text{w}$
$\text{q}=-\text{w}$
$\text{q}=+208\text{J}$ {heat absorbed so +ve}
$\text{w}=-208\text{J}$ {expansion so work done is -ve}