Answer:
To calculate the pressure when temperature and volume has changed, we use the equation given by combined gas law. The equation follows:
\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}
T
1
P
1
V
1
=
T
2
P
2
V
2
where,
P_1,V_1\text{ and }T_1P
1
,V
1
and T
1
are the initial pressure, volume and temperature of the gas
P_2,V_2\text{ and }T_2P
2
,V
2
and T
2
are the final pressure, volume and temperature of the gas
We are given:
\begin{gathered}P_1=760mmHg\\V_1=175L\\T_1=15^oC=[15+273]K=288K\\P_2=640mmHg\\V_2=198L\\T_2=?K\end{gathered}
P
1
=760mmHg
V
1
=175L
T
1
=15
o
C=[15+273]K=288K
P
2
=640mmHg
V
2
=198L
T
2
=?K
Putting values in above equation, we get:
\begin{gathered}\frac{760mmHg\times 175L}{288K}=\frac{640mmHg\times 198L}{T_2}\\\\T_2=274K\end{gathered}
288K
760mmHg×175L
=
T
2
640mmHg×198L
T
2
=274K
Hence, the temperature when the volume and pressure has changed is 274 K
