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
m(Fe2​O3​)n(Fe2​O3​)n(CO2​)m(CO2​)÷ M(Fe2​O3​)× 3/1× M(CO2​)

For the reaction Fe2O3 + 3CO → 2Fe + 3CO2, what mass m of CO2 forms from 32 g of Fe2O3? Assume the other reactants are in excess.

M(Fe2O3) = 159.69 g/molM(CO2) = 44.01 g/mol
m = g
2.Easy
m(CaCO3​)n(CaCO3​)n(CaO)m(CaO)÷ M(CaCO3​)× 1/1× M(CaO)

For the reaction CaCO3 → CaO + CO2, what mass m of CaO forms from 40 g of CaCO3? Assume the other reactants are in excess.

M(CaCO3) = 100.09 g/molM(CaO) = 56.08 g/mol
m = g
3.Medium
m(X)n(X)n(CO2​)m(CO2​)÷ M(X)× 1/ν× M(CO2​)

30 g of CH4 and 40 g of O2 react according to CH4 + 2O2 → CO2 + 2H2O. What mass m of CO2 can form?

M(CH4) = 16.04M(O2) = 32M(CO2) = 44.01 g/mol
m = g
4.Medium
m(X)n(X)n(NaCl)m(NaCl)÷ M(X)× 2/ν× M(NaCl)

6 g of Na and 10 g of Cl2 react according to 2Na + Cl2 → 2NaCl. What mass m of NaCl can form?

M(Na) = 22.99M(Cl2) = 70.9M(NaCl) = 58.44 g/mol
m = g
5.Hard
m(Mg)n(Mg)n(MgO)m(MgO)÷ M(Mg)× 2/2× M(MgO)

In the reaction 2Mg + O2 → 2MgO, 12 g of Mg reacts completely (the other reactants are in excess) and 18.7 g of MgO is collected. Find the percent yield Y.

M(Mg) = 24.31 g/molM(MgO) = 40.3 g/molactual: 18.7 g
Y = %
6.Hard
m(N2​)n(N2​)n(NH3​)m(NH3​)÷ M(N2​)× 2/1× M(NH3​)

In the reaction N2 + 3H2 → 2NH3, 8 g of N2 reacts completely (the other reactants are in excess) and 8.85 g of NH3 is collected. Find the percent yield Y.

M(N2) = 28.02 g/molM(NH3) = 17.03 g/molactual: 8.85 g
Y = %

Answer key

  1. 1. m = 26.46 g
  2. 2. m = 22.41 g
  3. 3. m = 27.51 g
  4. 4. m = 15.25 g
  5. 5. Y = 94 %
  6. 6. Y = 91.01 %

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