Consider the foi g reaction: C3H8(g) + 5O2 (g)---->3CO2(g) +4H2O(l). Propane

How many grams of CO2 are produced from18.5 g of oxygen gas and excess propane?

From your balanced equation:
5mol O2 gas will produce 3 mol CO2 gas.
Molar mass O2 = 32g/mol
18.5g O2 = 18.5/32 = 0.578 mol O2
This will produce 0.578*3/5 = 0.347 mol CO2
Molar mass CO2 = 44g/mol
0.347mol = 0.347*44 = 15.26g CO2 produced.