Physics - Heat & Thermo Question with Solution | TestHub
A real gas is filled inside a closed insulated rigid cylinder in the left portion. A diaphragm divides the cylinder in two equal parts and the right part of cylinder has vacuum. Suddenly this diaphragm breaks then temperature of gas will
Options:
Answer:
Solution:
The gas expands into vacuum (free expansion), so it does no work on the surroundings:
The cylinder is insulated, so no heat enters or leaves:
First law:
For an ideal gas, U depends only on T, so T would stay the same.
For a real gas, U also contains the intermolecular potential energy. Attractive forces become weaker as the molecules move apart, so the potential energy increases.
Total U is constant, so the kinetic energy decreases:
Kinetic energy is proportional to temperature, so the temperature of the gas decreases.
Answer: (B) decreases
