Consider a fixed amount of ideal gas in a container to which can be added an amount of thermal energy, Q.
(a) Suppose that when Q is added to the gas, the volume of the container does not change.
i What will the effect be, on the particles of gas, of adding thermal energy, Q ?
ii What will happen to the internal energy of the gas?
iii Does the gas do any mechanical work on its surroundings? Explain.
(b) Now suppose that, when Q is added to the gas, the pressure exerted by the gas remains constant, but the volume of the container changes.
i Adding Q to the gas will increase the average speed of the particles of the gas. Explain, using your ideas about kinetic theory, what must be happening for the pressure exerted by the gas to remain constant.
ii What is SI unit for the product of pressure and volume?
iii Write an algebraic expression for the work done by the gas on the surroundings in terms of the pressure of the gas and the change in volume of the container.
(c) i Generally, when thermal energy, Q, is added to some ideal gas, both the internal energy and the volume of the gas can change. Use the conservation of energy to write an expression relating Q to U and W .
ii What is the name usually given to your expression?