Chemistry practical

Tests for ions: three unknowns

Test three unknown solutions with sodium hydroxide, ammonia, silver nitrate, barium nitrate, acid and a flame, and name the ions in each.

What you will do

1. 01Pour a little of an unknown into a clean test tube for each test.
2. 02Add aqueous sodium hydroxide a few drops at a time, then in excess. If there is no precipitate, warm it and test the gas with damp red litmus.
3. 03Do the same with aqueous ammonia.
4. 04Acidify with dilute nitric acid, then add silver nitrate; and again with barium nitrate.
5. 05Add dilute hydrochloric acid and bubble any gas through limewater.
6. 06Clean the flame loop, dip it in the unknown and hold it in the flame.
7. 07Record every observation in words, then name the cation and anion in each unknown.