After the products return to STP, how many grams of nitrogen monoxide are present?

Question

When 37.5 L ammonia and 42.0 L oxygen gas at STP burn, nitrogen monoxide and water are produced. After the products return to STP, how many grams of nitrogen monoxide are present?

Answer 1

In reality many different nitrogen oxides will be formed. But based on this problem, let us assume that only nitrogen monoxide and water are formed:
4NH3 + 5O2 ==> 6H2O + 4NO
This balenced reaction shows that 5 Mol O2 is needed to react with 4 Mol NH3. Therefore, 42.0 L O2 can only react with 33.6 L of NH3. 42.0L of O2 is the limiting factor. Now, 33.6 L of NH3 will react with O2 to form 33.6 L of NO, with all the reactants and products in STP condition.