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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: MartynYarrow on December 15, 2007, 11:47:05 PM

Title: About acidify the oxalate solution
Post by: MartynYarrow on December 15, 2007, 11:47:05 PM
In redox titration, sodium oxalate is used as a primary standard to standardize the potassium permanganate solution. The sodium oxalate should be acidified with diluted sulphuric acid, but not hydrochloric acid.

I want to ask why the sodium oxalate can't be acidified with hydrochloric acid.
Moreover, can anyone tell why potassium permanganate should not be acidified?
THANK YOU!!!
Title: Re: About acidify the oxalate solution
Post by: Borek on December 16, 2007, 04:53:50 AM
http://www.chemicalforums.com/index.php?topic=15545.0
Title: Re: About acidify the oxalate solution
Post by: AWK on December 16, 2007, 05:00:58 AM
Quote from: MartynYarrow on December 15, 2007, 11:47:05 PM
In redox titration, sodium oxalate is used as a primary standard to standardize the potassium permanganate solution. The sodium oxalate should be acidified with diluted sulphuric acid, but not hydrochloric acid.

I want to ask why the sodium oxalate can't be acidified with hydrochloric acid.
Moreover, can anyone tell why potassium permanganate should not be acidified?
THANK YOU!!!


Permanganate will react with HCl too.
Title: Re: About acidify the oxalate solution
Post by: MartynYarrow on December 16, 2007, 05:32:17 AM
No one knows why sodium oxalate shouldn't be acidify with hydrochloric acid?
Title: Re: About acidify the oxalate solution
Post by: Borek on December 16, 2007, 05:46:54 AM
Quote from: MartynYarrow on December 16, 2007, 05:32:17 AM
No one knows why sodium oxalate shouldn't be acidify with hydrochloric acid?

You were already answered by AWK and I have pointed you to the thread where you can find answer to your question.
Title: Re: About acidify the oxalate solution
Post by: MartynYarrow on December 16, 2007, 09:19:28 AM
Quote from: Borek on December 16, 2007, 05:46:54 AM
Quote from: MartynYarrow on December 16, 2007, 05:32:17 AM
No one knows why sodium oxalate shouldn't be acidify with hydrochloric acid?

You were already answered by AWK and I have pointed you to the thread where you can find answer to your question.

my guess, HCl will be oxidized to toxic Cl2 gas by the KMnO4 since permanganate will react with HCl. Am I right?
Title: Re: About acidify the oxalate solution
Post by: Borek on December 16, 2007, 12:08:49 PM
Yep :) But the main problem here is not Cl2 toxicity.

This is side reaction. Will it influence final reasult of your titration?