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(Na)n(Na)n(NaCl)m(NaCl)÷ M(Na)× 2/2× M(NaCl)

For the reaction 2Na + Cl2 → 2NaCl, what mass m of NaCl forms from 40 g of Na? Assume the other reactants are in excess.

M(Na) = 22.99 g/molM(NaCl) = 58.44 g/mol
m = g
2.Easy
m(Mg)n(Mg)n(MgO)m(MgO)÷ M(Mg)× 2/2× M(MgO)

For the reaction 2Mg + O2 → 2MgO, what mass m of MgO forms from 50 g of Mg? Assume the other reactants are in excess.

M(Mg) = 24.31 g/molM(MgO) = 40.3 g/mol
m = g
3.Medium
m(X)n(X)n(NaCl)m(NaCl)÷ M(X)× 2/ν× M(NaCl)

12 g of Na and 32 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
4.Medium
m(X)n(X)n(MgO)m(MgO)÷ M(X)× 2/ν× M(MgO)

30 g of Mg and 24 g of O2 react according to 2Mg + O2 → 2MgO. What mass m of MgO can form?

M(Mg) = 24.31M(O2) = 32M(MgO) = 40.3 g/mol
m = g
5.Hard
m(H2​)n(H2​)n(H2​O)m(H2​O)÷ M(H2​)× 2/2× M(H2​O)

In the reaction 2H2 + O2 → 2H2O, 16 g of H2 reacts completely (the other reactants are in excess) and 78.66 g of H2O is collected. Find the percent yield Y.

M(H2) = 2.016 g/molM(H2O) = 18.02 g/molactual: 78.66 g
Y = %
6.Hard
m(CH4​)n(CH4​)n(H2​O)m(H2​O)÷ M(CH4​)× 2/1× M(H2​O)

In the reaction CH4 + 2O2 → CO2 + 2H2O, 20 g of CH4 reacts completely (the other reactants are in excess) and 36.85 g of H2O is collected. Find the percent yield Y.

M(CH4) = 16.04 g/molM(H2O) = 18.02 g/molactual: 36.85 g
Y = %

Answer key

  1. 1. m = 101.7 g
  2. 2. m = 82.89 g
  3. 3. m = 30.5 g
  4. 4. m = 49.73 g
  5. 5. Y = 55 %
  6. 6. Y = 82 %

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