Core practical 12 - Prepare a transition metal complex

Write the equation for this reaction.

CuSO₄•5H₂O + 4NH₃ → Cu(NH₃)₄SO₄•H₂O + 4H₂O

Calculate the relative formula masses of CuSO₄•5H₂O and Cu(NH₃)₄SO₄•H₂O

CuSO₄•5H₂O = 249.5

Cu(NH₃)₄SO₄•H₂O = 245.5

Calculate the number of moles of copper(II) sulfate used in the reaction.

0.00601 moles (based on 1.5g of CuSO₄•5H₂O)

Use your answer to calculate the theoretical yield of tetraamminecopper(II) sulfate-1-water your reaction should have produced.

Theoretical yield of Cu(NH₃)₄SO_4^.H₂O = 1.48g.

Calculate the percentage yield obtained in this reaction.

Percentage yield = 1.2/1.48 × 100 = 81%.

Comment on your percentage yield. Explain any loss or gain in mass compared with the theoretical yield.

Losses could be due to reaction not going to completion and some product staying in solution and not crystallising out; gains could be due to crystals not being dry or not being pure.