# How does the ideal gas law differ from the combined gas law?

The combined gas law describes states that $\frac{P V}{T} = k$ is a constant for any fixed quantity of gas, but the ideal gas law extends this to say that the value of the constant is proportional to the number of moles of gas, $k = n R$.
Thus, the ideal gas law states that $\frac{P V}{T} = n R$ where $R$ is the universal gas constant, $R = 8.314$ J/(mol-K). Multiplying both sides by $T$, we can rewrite the ideal gas law in a more conventional form:
$P V = n R T$.