Percentage Yield Calculations

Percentage yield = actual yield cx 100% theoretical yield

The actual yield is given in the question.The theoretical yield is calculated using a balanced equation.

Worked exampleIn a reaction 330kg of carbon dioxide was produced when 120kg of carbon was burned. Calculate the percentage yield.

Find the theoretical yield using a balanced equation.

C + O2CO2

12g44g12kg44kg120kg440kg

Calculate percentage yield

Actual yield x 100% = 330 x 100=75%Theoretical yield 440

Examples for practice

A) 10.2g of 1, 2dibromopropane (C3H6Br2) was obtained from 2.6g of propene (C3H6).

C3H6 + Br2 C3H6Br2Calculate the percentage yield.(ans = 81.6%)

B) 1g of hydrogen reacts with excess nitrogen to produce 5g of ammonia.

N2 + 3H2 2NH3Calculate the percentage yield.(ans = 88.2%)

C) Under test conditions 1 tonne of sulphur dioxide reacts with excess oxygen to produce 0.8 tonnes of sulphur trioxide.

2SO2 + O22SO3Calculate the percentage yield.(ans = 64%)

2000 (Section B 14a, iii)

2002 (Section B 10d)

2003 (Section B 6c)

2004 (Section A 22)

2006 (section B 7c, iii)

2007 (Section B 8c

2009 (Section B 8C)

2010 (section B 10b)

2011 (Section B 8b)

2012 (Section B 10c)

2013 (Section B 11b)