OCR A-Level Chemistry Ion Tests

Test for Cu2+

Add aqueous sodium hydroxide.

Blue solution to blue ppt

Test for Fe2+

Add aqueous sodium hydroxide.

Pale green solution to green ppt

Test for Mn2+

Add aqueous sodium hydroxide.

Pale pink solution to light brown ppt

Test for Cr3+

Add aqueous sodium hydroxide.

Violet solution to green ppt

Test for Fe3+

Add aqueous sodium hydroxide.

Pale yellow solution to orange brown ppt

Which halide is soluble in dilute ammonia

Chloride

Test for sulfate ions

Add nitric acid, then barium nitrate, white ppt

Which halide is insoluble in conc ammonia

Iodide

Which halide is soluble in conc ammonia but insoluble in dilute ammonia

Bromide

In what order do you test for anions

Carbonate, sulfate, halide

Why do you test carbonates first?

barium carbonate and silver carbonate are insoluble if carbonate ion is present, it will give a false positive in halide and sulfate tests