A cylinder with a valve at the bottom contains an ideal gas. The valve is opened and some of the gas escapes slowly. The valve is then closed, after which the piston is observed to be at a lower position. Assume that the system is in thermal equilibrium with the surroundings at all times and that the piston is free to move without friction. Is the final pressure of the gas in the cylinder greater than, less than, or equal to the initial pressure?

Question

Nicolas Porter

Physics

25 May, 01:11

A cylinder with a valve at the bottom contains an ideal gas. The valve is opened and some of the gas escapes slowly. The valve is then closed, after which the piston is observed to be at a lower position. Assume that the system is in thermal equilibrium with the surroundings at all times and that the piston is free to move without friction. Is the final pressure of the gas in the cylinder greater than, less than, or equal to the initial pressure?

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Answers (1)

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Mollie Macdonald · Answer 1

Pressure of the gas increases

Explanation:

As the gas escapes from the cylinder and the new position of the piston is lowered, it means the volume of the gas decreased.

According to the question, the system is in thermal equilibrium, it means the temperature of the gas and the surroundings remains same.

So, by use of ideal gas equation

P V = R T

as temperature is constant so, P V = constant

The volume of the gas decreases, so the pressure of the gas increases.