Question

A heat engine carries 1 mole of an ideal monoatomic gas around the cycle as shown in the figure, the amount of heat added in the process AB and heat removed in th process CA are:

• A. $q_{AB}=450R$ and $q_{CA}=-450$ R
• B. $q_{AB}=450R$ and $q_{CA}=-225$ R
• C. $q_{AB}=450R$ and $q_{CA}=-375$ R
• D. $q_{AB}=375R$ and $q_{CA}=-450$ R

Answer 1

The correct option is C $q_{AB}=450R$ and $q_{CA}=-375$ R

Case I For process AB:
$△T=T_2-T_1=600-300=300K$
$n=1$
$C_v=\frac{3}{2}R$ (for monoatomic gas)
At constant volume heat abosrbed is given as:
$△U=q_v=n{C}_{v,m}△T=\frac{3}{2}R\times 300=450R$

Case II For process CA:
$△T=T_2-T_1=300-450=-150K$
$n=1$
$C_p=\frac{5}{2}R$ (for monoatomic gas)
At constant pressure heat removed is given as:
$△H=q_p=n{C}_{p,m}△T=\frac{5}{2}R(-150)=-375R$