why does sodium carbonate extract need to be acidified?

Question

while doing qualitative inorganic salt analysis, why does sodium carbonate extract need to be acidified with an acid besides the acid radical?

Answer 1

Think it over - sodium carbonate is fairly alkaline and this leaves an alkaline residue in the extracted solution. What sort of issue does this raise?

This alkalinity may induce, over time, some undesired reactions - as I suspect you have concluded by now.

What would a carefully conducted acidification do? What would a carelessly conducted acidification do? Think this over.

Carefully conducted, using a moderate acid for the conditions would neutralize the excess alkalinity.

Carelessly conducted acidification would either over acidify and enable acid induced undesirable reactions or underneutralize the excess alkalinity and not resolve the initial excess alkalinity condition.

Think over what I said and make sure you understand it.