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 A to B and heat removed in the process C to A are:

• A. $q_{AB}=450R$ and $q_{CA}=-450R$
• B. $q_{AB}=450R$ and $q_{CA}=-225R$
• C. $q_{AB}=375R$ and $q_{CA}=-250R$
• D. $q_{AB}=375R$ and $q_{CA}=-450R$

Answer 1

The correct option is C $q_{AB}=375R$ and $q_{CA}=-250R$

Case I For process AB:
$△T=T_2-T_1=600-350=250K$
$n=1$
$C_v=\frac{3}{2}R$ (for monoatomic gas)
At constant volume heat absorbed is given as:
$△U=q_v=n{C}_{v,m}△T=\frac{3}{2}R\times 250=375R$

Case II For process CA:
$△T=T_2-T_1=350-450=-100K$
$n=1$
$C_p=\frac{5}{2}R$ (for monoatomic gas)
At constant pressure heat removed is given as:
$△H=q_p=n{C}_{p,m}△T=\frac{5}{2}R(-100)=-250R$