The decomposition of a silver oxide sample forms 15.8 g of Ag(s):
2 Ag2O(s) → 4Ag(s) + O2(g)
What total volume of O2 gas forms if it is collected over water at a temperature of 25 °C and a total pressure of 752 mm Hg?
Your reaction will produce 0.94 L of oxygen gas.
The first thing you need to do is determine how many moles of oxygen gas are produced when that much silver is produced. To do this, use the number of moles of silver and the mole ratio that exists between the two products.
Notice that you have a 4:1 mole ratio between silver and oxygen, which means that you get 1 mole of oxygen for every 4 moles of silver produced.
The number of moles of silver the reaction produced is
15.9g⋅1 mole Ag/107.87g=0.1474 moles Ag.
This means that you'll get