How to identify if sodium carbonate and sodium phosphate is present in a solution? (1 Viewer)

[The Savior]

How to identify if sodium carbonate and sodium phosphate is present in a solution? Say if i had several compounds including lead nitrate, copper nitrate, barium nitrate, sodium carbonate, and sodium phosphate in different solutions. We are asked to identify which two solutions contain the sodium carbonate and sodium phosphate. Would it be sufficient to perform a flame test first to isolate the two sodium compounds, and then perform an anion test and add HNO3 to test for effervescence? Cause this would isolate the carbonate and then we can test the other solution to make sure we definitely have phosphate, we would take a fresh sample and add HNO3 and a solution containing an ammonium compound to obtain a yellow precipitate. Are these steps correct? Thanks for helping out a hopeless chemistry student.

 

[Ekman]

Re: How to identify if sodium carbonate and sodium phosphate is present in a solution

Well you aren't wrong for using a flame test to test the presence of sodium, and the addition of an acid to a carbonate does in fact produce a colourless gas (CO2), which can prove the presence of the carbonate. However I don't agree with adding ammonium, as ammonium is always soluble with any anion, so it wouldn't really produce a precipitate. So instead what I would do is to add NaOH to increase the pH, then add BaCl2 to form a white precipitate, proving the presence of phosphate, as Ba3(PO4)2 only forms in basic solutions.

 

[The Savior]

Re: How to identify if sodium carbonate and sodium phosphate is present in a solution

we dont have any barium chloride, would barium nitrate suffice?

 

[Ekman]

Re: How to identify if sodium carbonate and sodium phosphate is present in a solution

we dont have any barium chloride, would barium nitrate suffice?

Yes, since we only need a source of barium ions to precipitate out with the phosphate.