Question

What would be the most appropriate test to differentiate potassium carbonate from lithium sulcate and why?

Answer 1

Answer on Question#38672, Chemistry, Other

Apparently, the most appropriate and simple test to differentiate potassium carbonate from lithium sulfate is pH-test of water solutions of these salts.

Potassium carbonate $(\mathrm{K}_2\mathrm{CO}_3)$ forms a strongly alkaline solution due to partial hydrolysis:

$$\mathrm{K}_2\mathrm{CO}_3 \rightarrow 2\mathrm{K}^+ + (\mathrm{CO}_3)^{2-}$$ $$(\mathrm{CO}_3)^{2-} + \mathrm{H}_2\mathrm{O} \rightleftharpoons (\mathrm{HCO}_3)^- + \mathrm{OH}^-$$

The alkalinity can be easy detected using reagent paper (litmus).

Conversely, pH of lithium sulfate $(\mathrm{Li}_2\mathrm{SO}_4)$ will be closely to 7 (neutral) because no hydrolysis occurs in this case. The salt will be dissociated only:

$$\mathrm{Li}_2\mathrm{SO}_4 \rightarrow 2\mathrm{Li}^+ + (\mathrm{SO}_4)^{2-}$$