General Chemistry

Question

Copper(II) ions can be displaced by aluminum metal.

3 CuSO₄(aq) + 2 Al(s) → Al₂(SO₄)₃(aq) + 3 Cu(s)

How many grams of Al would be needed to displace all of the copper ions in 37.9 mL of 0.550 M CuSO₄?  g

 

How many grams of Cu would be recovered from the copper ions in 37.9 mL of 0.550 M CuSO₄?   g

Answer 1

3 CuSO₄(aq) + 2 Al(s) ==> Al₂(SO₄)₃(aq) + 3 Cu(s) ... balanced equation

Using dimensional analysis:

37.9 ml CuSO₄ x 1 L / 1000 ml x 0.550 mol / L = 0.02085 mols CuSO₄

0.02085 mol CuSO₄ x 2 mol Al / 3 mol CuSO₄ = 0.01390 mols Al needed

0.01390 mols Al x 26.98 g Al / mol = 0.375 g Al needed (to 3 sig. figs.)

Grams of Cu = 0.02085 mols CuSO₄ x 1 mol Cu / mol CuSO₄ x 63.55 g Cu / mol = 1.33 g Cu (3 sig.figs.)