GC Bootcamp question

[emminent]

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Adding sodium oxalate to a solution of oxalic acid causes the pH to: increase due to common ion effect

I get why answer is that but just wondering wouldn't adding conjugate base to the acid make a buffer?

 

[dawg289]

Your statement is almost correct. Buffers are made by mixing a weak acid and its conjugate base. Do not confuse a weak acid/base with a conjugate acid/base of a strong acid. For example, HCl is a strong acid, but Cl- is so weak it's not considered a base.

 

[emminent]

Your statement is almost correct. Buffers are made by mixing a weak acid and its conjugate base. Do not confuse a weak acid/base with a conjugate acid/base of a strong acid. For example, HCl is a strong acid, but Cl- is so weak it's not considered a base.

Though, since oxalic acid isn't considered one of the strong acid isn't it a weak acid and the oxalate is it's conjugate base? Sorry if I'm not getting this thru my head.

 

[dawg289]

Yes! I didn't explicitly answer your question with respect to oxalic acid. Carboxylic acids are weak acids.