If 120. g of propane, C3H8, is burned in excess oxygen according to the following equation: C3H8 + 5O2  3CO2 + 4H2O, how many grams of water are formed?

Answer 1

Molecular mass of propane (C3H8)
= 3*12+8*1
= 44

Molecular mass of water (H2O)
= 2*1+1*16
= 18

using the balanced equation, we find that the ratio
mass of propane : mass of water
= 1*44 : 4 * 18
= 44 : 72

Hence the mass of water can be calculated.

Note: replace the above approximate atomic masses by the exact values and repeat above calculations.

Answer 2

196.36g