20 mL of ##N_2## gas is equivalent to 0.025 grams of ##N_2##.

First, you need to know the ideal gas law, which states that one mol of an ideal gas (at standard temperature and pressure – STP) takes up 22.4 L of volume. Therefore, you can extrapolate that an unknown mol of ##N_2## would equal 20 mL in STP. By doing the math, you can calculate the mol of ##N_2## in this equation using the following formula: ##1/22.4## =##x/0.02##. Therefore, 20 mL of ##N_2## is roughly equivalent to 0.000893 mol of ##N_2##.

In one mol of ##N_2## there are 28.02 grams of mass (the molecular weight of ##N## multiplied by two = 28.04 = one mol of ##N_2##).

Doing more math, that brings us to 0.000893 mol x 28.04 grams = 0.025 grams of ##N_2##.