qualitative analysis of ions on a test-tube scale; processes and techniques needed to identify the following ions in an unknown compound:

(i) anions:
- CO₃^2–, by reaction with H⁺_(aq) forming CO_2(g) (see 2.1.4c)
- SO₄^2–, by precipitation with Ba²⁺_(aq)
- Cl^–, Br^–, I^– (see 3.1.3g)

(ii) cations: NH₄⁺, by reaction with warm NaOH_(aq) forming NH₃.

Sequence of tests required is carbonate, sulfate then halide. (BaCO₃ and Ag₂SO₄ are both insoluble.)
PAG4