For the combustion of methane, beginning with 3.15 mole of CH4 .
How many moles of H2O are obtained when the CH4 is completly combusted?
The balanced chemical equation for the combustion of methane is:
CH4 + 2O2 -> CO2 + 2H2O
This equation shows that for every one mole of CH4 combusted, two moles of H2O are produced.
Therefore, for 3.15 moles of CH4 completely combusted, the amount of H2O produced would be:
3.15 mol CH4 x 2 mol H2O/1 mol CH4 = 6.3 mol H2O
So, 6.3 moles of H2O would be obtained when 3.15 moles of CH4 is completely combusted.