Test Index

Thermodynamics

© examsnet.com
Question : 4 of 10
Marks: +1, -0
A cylinder with a movable piston contains 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of a heat insulator, and the piston is insulated by having a pile of sand on it. By what factor does the pressure of the gas increase if the gas is compressed to half its original volume?
Solution:  
As the gas is completely insulated, the process is adiabatic.
P1V1γ=P2V2γP_{1} V_{1}^{\gamma}=P_{2} V_{2}^{\gamma}
⇒P2P1=(V1V2)γ\Rightarrow \frac{P_{2}}{P_{1}} = \left(\frac{V_{1}}{V_{2}}\right)^{\gamma}
P2P1=(V1V12)1.4(∴V2=12V1γ=1.4 Given)\frac{P_{2}}{P_{1}} = \left(\frac{V_{1}}{\frac{V_{1}}{2}}\right)^{1.4} \begin{pmatrix} \therefore V_{2}= \frac{1}{2} V_{1} \\ \gamma=1.4 \text{ Given} \end{pmatrix}
P2P1=(2)1.4=2.64\frac{P_{2}}{P_{1}} = (2)^{1.4} = 2.64
© examsnet.com
Go to Question: