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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Fmeub on August 02, 2008, 12:15:10 PM

Title: Why use sodium metabisulfite in copper(I)chloride preparation?
Post by: Fmeub on August 02, 2008, 12:15:10 PM

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.

Title: Re: Why use sodium metabisulfite in copper(I)chloride preparation?
Post by: AWK on August 04, 2008, 05:13:51 AM

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