If you burn 55.6 g of hydrogen and produce 497 g of water, how much oxygen reacted?

2H2 + O2 → 2H2O
2 mol H2 + 1mol O2 will produce 2 mol H2O
Molar mass H2O = 18.0153g/mol
497g H2O = 23.813 mol H2O produces
This will require 27.587/2 = 13.793 mol O2

Molar mass O2 = 32g/mol
13.793mol = 13.793*32 = 441.37g O2 required.

The easiest way is subtracting 55.6 from 497 which gives you 441.4.

The gas would begin to expand, and eventually the can would burst or explode.