2 Answers

To go from liters to grams, divide your liters by 22.4 L (volume of ideal gas at STP) and then multiply by the molar mass. So…
11.2 L / 22.4 L = .5 mol
.5 mol * 28 g/mol (diatomic molecule) = 14 grams N2
Hope this helps.
Source(s): Biochem major, SUNY Binghamton 
At STP (0 degrees C, and 1 atmosphere), 1 mole of gas occupies 22.4 Liters of volume. Since you have exactly 11.2 L of volume in this case, you have exactly 0.5 moles of gas.
11.2 Liters x 1 mole/22.4 Liters = 0.5 moles