336 liters of ammonia (at standard) has a mass.

We calculate the amount of ammonia corresponding to 336 liters:

n (NH3) = V (NH3): Vm = 336: 22.4 = 15 mol, (here V is the volume of ammonia, Vm is the molar volume of any gas, a constant value always equal to 22.4 l / mol).

Let’s calculate the molar mass of ammonia (it is numerically equal to the relative molecular mass, calculated in the same way):

M (NH3) = 14 + 3 × 1 = 17 g / mol.

We find the mass of ammonia:

m (NH3) = n (NH3) × M (NH3) = 15 × 17 = 255 (g).