Question

Steam is stored in a 0.3m3

rigid tank, initially at 7bar and 440oC. After a long 

time, steam temperature was measured and found to be 240oC. Find the final 

pressure as well as work and heat exchanged during that time.

Answer 1

Gives

$$T_1=440°C=713K,T_2=240°C=513K,P_1=7bar$$

We know that

Pv=nRT

Case (1)

$P_1V_1=nRT_1$

Case (2)

$P_2V_2=nRT_2$

Gives

$V_1=V_2$

Both eqution we can written as

$\frac{P_1}{P_2}=\frac{T_1}{T_2}$

$P_2=\frac{T_2}{T_1}\times P_1$

$P_2=\frac{713}{513}\times7=9.72bar$