Chem question

Question

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

a.) Write a balanced chemical equation for this reaction.

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

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

Answer 1

a) NH₃ + O₂ + CH₄ = HCN + H₂O

Because N and C are only 1 atom each on both sides, then coefficients of NH₃, CH₄ and HCN must all be the same. Coefficient of H₂O must be 2*Coefficent of O₂.

 

trying 1,1,1,1,2 doesn't work

trying 1,2,1,1,4 doesn't work

trying 2,3,2,2,6 DOES work

 

So it's  2NH₃ + 3O₂ + 2CH₄ = 2HCN + 6H₂O 

 

b) Since the Limiting Reactant is O₂, we can calculate the HCN as:

 

   225 gO₂ * 1mole O₂/32.0g O₂ * 2 mole HCN/3 mole O₂ * 27.03g HCN/1 mole HCN = 126.7→ 127g HCN

 

   You calculate H₂O similarly:

 

225 gO₂ * 1mole O₂/32.0g O₂ * 6 mole H₂O/3 mole O₂ * 18.02 g H₂O/1 mole H₂O = 253.4 → 253g H₂O

 

c) % yield = actual yield/theoretical yield * 100, so that's:

 

105/127 * 100 = 82.7%