ACE Academy

Reacting Mass Calculator

The mole is at the heart of every calculation.

Worked example

Which reactant limits the thermite reaction?

Fe₂O₃ + 2Al → 2Fe + Al₂O₃

Iron(III) oxide mass gAluminium mass g

1Convert mass to molesFe₂O₃: 0.50625 mol
Al: 1.92593 mol

2Divide by the coefficientFe₂O₃: 0.50625
Al: 0.96296

3Use the smaller valueFe₂O₃ is limiting

4Find the iron produced1.0125 mol · 56 = 56.7 g

MOLES

mass moles ratio moles mass

Limiting reactantFe₂O₃

Fe₂O₃81 g0.5063 mol

Al27.338 g1.0125 mol

Fe56.7 g1.0125 mol

Al₂O₃51.637 g0.5063 mol

Predicted reacting masses assume complete reaction.