# Gas laws confusion

by ghostanime2001
Tags: confusion, laws
 Admin P: 23,363 $$\frac{PV}{nT} = R$$ For every sample of the ideal gas $\frac{PV}{nT}$ has exactly the same value. That means when preparing a gas sample you have only a limited number of degrees of freedom - you can select any three parameters, but the fourth one will be a function of these three. $\frac{PV}{nT}$ is a constant. In other cases we are limiting number of parameters we change. For example when we say PV=const we mean - if we keep nT constant (for example we can do experiments without allowing gas to escape nor enter the vessel, and we allow it to have the same temperature all the time), PV is a constant as well. Or when we say $\frac V T = const$ we mean it is constant as long as $\frac P n$ doesn't change (again, many ways to design an experiment this way).