Question

A sample of 8.5 g nh3 on oxidation produces 4.5 g of no. calculate the percent yield. reaction: 4 nh3 5 o2 → 4 no 6 h2o

Answer 1

30.% Determine the molar mass of NH3 and NO Atomic weight nitrogen = 14.0067 Atomic weight hydrogen = 1.00794 Atomic weight oxygen = 15.999 Molar mass NH3 = 14.0067 + 3 * 1.00794 = 17.03052 g/mol Molar mass NO = 14.0067 + 15.999 = 30.0057 g/mol Moles NH3 = 8.5 / 17.03052 = 0.499103962 mol Moles NO = 4.5 / 30.0057 = 0.149971505 mol Looking at the balanced equation, for every mole of NH3 consumed, you should get one mole of NO. So if we had 100% yield, we should have 0.499103962 moles of NO. But we don't. The percent yield is a simple matter of division by what we did get by what we should get. So 0.149971505 / 0.499103962 = 0.300481497 = 30.0481497% Rounding to 2 significant figures gives 30.% yield.