How to calculate % yield and write equation?

Question

When ammonia gas, oxygen gas and methane gas (CH4) are combined, the products are hydrogen cyanide gas and water.

A) Write a balanced equation.

B) Calculate the mass of each product produced when 225 g of oxygen gas is reacted with an excess of the other two reactants.

C) If the actual yield of the experiment in B is 105 g HCN, calculate the percent yield.

Answer 1

2NH3 + 3O2 + 2CH4 => 6H2O + 2HCN

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B) Calculate the mass of each product produced when 225 g of oxygen gas is reacted with an excess of the other two reactants, using molar masses:

225 g O2 @ (6 mol) (18g/mol H2O) / (3mol) (32 g/mol O2) = 253 g H2O

225 g O2 @ (2mol) (27.03 g/mol HCN) / (3mol) (32 g/mol O2) = 127 g HCN

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C) If the actual yield of the experiment in B is 105 g HCN, calculate the percent yield.

105 / 126.7 times 100 = 82.87

your answer: 82.3% yield