Question

an ideal gas of monotonic molecules expands from its initial state A to a state B through an isobaric process and then further expands to a volume C . Find the work done by the gas ,increase in internal energy, and the energy transferred by heat to the gas over the whole process

Answer 1

$A_{AB}=p_1\Delta V=4\cdot 1.49=5.96~J,$

$A_{BC}=\frac{p_2V_2}{\gamma -1}(1-(\frac{V_2}{V_3})^{\gamma -1})=\frac{4\cdot 3.49}{2/3}\cdot(1-(\frac{3.49}{8})^{2/3})=8.90~J,$

$A=5.96+8.90=14.86~J,$

$\Delta U_{AB}=\frac 32 p_1 \Delta V=8.94~J,$

$\Delta U_{BC}=-A_{BC}=-8.90~J,$

$\Delta U=8.94-8.90=0.04~J,$

$Q_{AB}=A_{AB}+\Delta U_{AB}=5.96+8.94=14.90~J,$

$Q_{BC}=0~J,$

$Q=14.90+0=14.90~J.$