Stoichiometry worksheet with answers

Free printable Stoichiometry worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

For the reaction C₃H₈ + 5O₂ → 3CO₂ + 4H₂O, what mass m of CO₂ forms from 25 g of C₃H₈? Assume the other reactants are in excess.

M(C₃H₈) = 44.1 g/molM(CO₂) = 44.01 g/mol

m = g

2.Easy

For the reaction CH₄ + 2O₂ → CO₂ + 2H₂O, what mass m of H₂O forms from 10 g of CH₄? Assume the other reactants are in excess.

M(CH₄) = 16.04 g/molM(H₂O) = 18.02 g/mol

m = g

3.Medium

16 g of Fe₂O₃ and 32 g of CO react according to Fe₂O₃ + 3CO → 2Fe + 3CO₂. What mass m of CO₂ can form?

M(Fe₂O₃) = 159.69M(CO) = 28.01M(CO₂) = 44.01 g/mol

m = g

4.Medium

24 g of C₃H₈ and 10 g of O₂ react according to C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. What mass m of H₂O can form?

M(C₃H₈) = 44.1M(O₂) = 32M(H₂O) = 18.02 g/mol

m = g

5.Hard

In the reaction 2Mg + O₂ → 2MgO, 20 g of Mg reacts completely (the other reactants are in excess) and 27.19 g of MgO is collected. Find the percent yield Y.

M(Mg) = 24.31 g/molM(MgO) = 40.3 g/molactual: 27.19 g

Y = %

6.Hard

In the reaction 2Mg + O₂ → 2MgO, 24 g of Mg reacts completely (the other reactants are in excess) and 32.62 g of MgO is collected. Find the percent yield Y.

M(Mg) = 24.31 g/molM(MgO) = 40.3 g/molactual: 32.62 g

Y = %

Answer key

1. m = 74.85 g
2. m = 22.47 g
3. m = 13.23 g
4. m = 4.505 g
5. Y = 82.01 %
6. Y = 81.99 %

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