Since the number of moles of the gas is not given, a first response to this problem might be that there is not enough information to solve it using the ideal gas law. In fact, since the temperature is the only quantity affecting the change in volume, all that is needed is Charles's law:
Equation (7) holds because Charles's law simply states that the ratio of the volume of a gas to its temperature is a constant. Since the ratio is constant, it must be the same before and after the temperature change. Substituting into equation (7) gives
The ideal gas law gives a definition of density. The quantity n represents the number of moles of the gas present. If this quantity is multiplied by the mass per mole M, the amount of mass of the gas is given.
