[Fmeub]

Hi!

Given the following reaction equations:

Na₂S₂O₅ + H₂O -> 2NaHSO₃

and

2CuSO₄.5H₂O + 4NaCl + NaHSO₃ + NaOH -> 2CuCl + 3Na₂SO₄ + 2HCl + 10H₂O

In the procedure for an experiment I have to do, it says that I mix Na₂S₂O₅ , NaOH and water, and then add this to a hot mixture of CuSO₄.5H₂O , NaCl and water.

My question is why use sodium metabisulfite (Na₂S₂O₅ ), and not just sodium bisulfite (NaHSO₃) or sodium sulfite (Na₂SO₄) to start with?

Later the CuCl is used in the synthesis of o-chlorobenzoic acid.

[AWK]

You should rerduce Cu(II) to Cu(I)