Percentage Yield

Question

Gaseous methane reacts with gaseous oxygen gas to produce gaseous carbon dioxide and gaseous water . If 3.56 g of carbon dioxide is produced from the reaction of 1.8 g of methane and 9.6 g of oxygen gas, calculate the percent yield of carbon dioxide.

Be sure your answer has the correct number of significant digits in it.

Answer 1

Write the balanced equation:

CH4 + 2O2 ==> CO2 + 2H2O

Find limiting reactant:

moles CH4 = 1.8 g x 1 mol/ 16 g = 0.1125 mol

moles O2 = 9.6 g x 1 mol/32 g = 0.30 mol

Since the mol ratio of O2 to CH4 is 2:1, we see that CH4 is limiting.

Theoretical yields of CO2 = 0.1125 mol CH4 x 1 mol CO2/molCH4 = 0.1125 mols CO2 x 44 g/mol = 4.95 g CO2

% yield = 3.56 g / 4.95 g (x100) = 71.9%