Question

When 229 J of energy is supplied as heat at constant pressure to 3 mol Ar(g), the temperature of the sample is increased by 2.55K. Calculate the molar heat capacity at constant volume:

• A. $30kJ{K}^{-1}{mol}^{-1}$
• B. $30J{K}^{-1}{mol}^{-1}$
• C. $21.7J{K}^{-1}{mol}^{-1}$
• D. $21.7KJ{K}^{-1}{mol}^{-1}$

Answer 1

The correct option is C $21.7J{K}^{-1}{mol}^{-1}$

$229=n{C}_P\Delta T$

$\to C_P=\frac{229}{3\alpha 2.55}=29.93J/K$

$C_V=C_P-R$

$=21.63J/K$

$\approx 21.7J/K$