Answer to Question #138654 in Physical Chemistry for Eli Drew

Question

Determine the limiting reactant when 3g of ammonia reacts with 6g of oxygen to produce H2O and nitrogen monoxide

Answer 1

4NH3 +5 O2 --> 4NO +6H2O

is the balanced reaction 

mass of NH3 present = 3 g

mols of NH3 present = 3 g/17.03 g/mol = 0.1762 mol

mass of O2 present = 6g

mols of O2 present = 6 g/32 g/mol = 0.1875 mol

 4 mol NH3 need 5 mol O2

thus 

0.1762 mol NH3 need 5 mol O2/4mol NH3 *0.1762 mol NH3

= 0.220 mol O2 is needed

But available O2 is 0.1875 mol , which is fewer than required

mols

Thus limiting reactant = O2

Answer

Limiting reactant = O2