A quantity of $\mathrm{N}_{2}$ occupies a volume of $1.0 \mathrm{~L}$ at $300 \mathrm{~K}$ and $1.0 \mathrm{~atm} .$ The gas expands to a volume of $3.0 \mathrm{~L}$ as the result of a change in both temperature and pressure. Find the density of the gas at these new conditions.