Question

What mass of water is produced from the complete combustion of 2.60×10−3 g of methane?

Answer 1

CH4 + 2O2 ==> CO2 + 2H2O

mols CH4 = grams CH4/molar mass CH = 0.00260/16 = 0.0001625
Convert to mols H2O formed using the coefficients in the balanced equation.
0.0001625 x (2 mol H2O/1 mol CH4) = 0.0001625 x 2 = 0.000325
grams H2O = mols H2O x molar mass H2O = ? g