An ideal gas with fixed amount and temperature undergoes a volume halving. What happens to its pressure?

An ideal gas with fixed amount and temperature undergoes a volume halving. What happens to its pressure?

• A. Pressure halves.
• B. Pressure doubles.
• C. Pressure remains the same.
• D. Pressure quadruples.

Answer: (B)

Pressure is inversely proportional to volume when the amount of gas and the temperature are held fixed (PV = nRT). Since n and T don’t change, PV stays constant, so P ∝ 1/V. If the volume is halved, the pressure must double to keep PV the same. This happens because the gas molecules collide with the container walls more often in the smaller volume, increasing the force per unit area. The pressure would not stay the same, nor would it jump by a larger factor unless the temperature or the amount of gas changed.

Pressure is inversely proportional to volume when the amount of gas and the temperature are held fixed (PV = nRT). Since n and T don’t change, PV stays constant, so P ∝ 1/V. If the volume is halved, the pressure must double to keep PV the same. This happens because the gas molecules collide with the container walls more often in the smaller volume, increasing the force per unit area. The pressure would not stay the same, nor would it jump by a larger factor unless the temperature or the amount of gas changed.