Testing for Ammonia
- Ammonia is a gas with a pungent smell that turns damp red litmus paper blue
- Hold the litmus paper near the mouth of the test tube
- If you are testing for ammonia produced from ammonium ions and sodium hydroxide, avoid touching the sides prevents traces of sodium hydroxide from also turning the red litmus paper blue
Diagram showing how to perform the test for ammonia gas
Damp red litmus paper turns blue in the presence of ammonia
Examiner Tip
- Make sure you understand the difference between ammonium and ammonia. Ammonium refers to the aqueous cation, NH4+, whereas ammonia is the gas, NH3.
- The pungent smell ammonia gives off is not a chemical test-- this would be the damp red litmus paper turning blue.
