Identify the relevant wet test for $\mathrm{Ba}^{2+}$

In qualitative inorganic analysis, cations are often detected by adding a reagent that gives a characteristic insoluble precipitate.

Check the possible precipitates of $\mathrm{Ba}^{2+}$

• $\mathrm{BaSO_4}$: This is a very insoluble white precipitate.
• $\mathrm{Ba(OAc)_2}$ (barium acetate): This is soluble in water, so it is not used as a precipitate test.
• $\mathrm{BaCO_3}$: This is also an insoluble white precipitate.
• Barium oxalate, $\mathrm{BaC_2O_4}$: also sparingly soluble and can precipitate.

Determine the standard confirmatory wet test

For detection of $\mathrm{Ba}^{2+}$ in salt analysis, the common confirmatory precipitation test is addition of carbonate ion to produce:

This gives a white precipitate of barium carbonate.

Evaluate options

• A: $\mathrm{BaSO_4}$ — insoluble, but not the usual wet test asked here.
• B: $\mathrm{Ba(OAc)_2}$ — incorrect, soluble.
• C: $\mathrm{BaCO_3}$ — correct.
• D: Barium oxalate — can precipitate, but not the standard answer here.

Final answer

The precipitate obtained for detection of $\mathrm{Ba}^{2+}$ is:

Comparison with stored answer

Stored correct answer: C

My derived answer: C

Hence, they agree.