What will be the mass of a 3 L sample of oxygen gas at STP?

Question

Just looking for some help on this

Answer 1

Recall that at STP the volume of 1 mole of any ideal gas will be 22.4 liters. Put another way, 22.4 L = 1 mol.

3 L x 1 mole/22.4 L = 0.134 moles O2 gas. Since the molar mass of O2 = 32g/mole, we have...

0.134 moles x 32 g/mole = 4.29 g = 4 g (to 1 significant figure)