Specification Point 2.47:
Describe tests for these cations: NH4+ Using Sodium Hydroxide Solution and identifying the gas evolved, Cu2+, Fe2+ and Fe3+ using Sodium Hydroxide Solution
Cations: A positively charged ion.
Test for Ammonium Ion NH4+
The test for Ammonium Ion
- Add aqueous sodium hydroxide to the solid or solution and heat
- Lower damp red litmus paper into gas produced
- If ammonium ions are present then a pungent-smelling gas is produced
- The gas produced turns damp red litmus paper blue
- The gas in ammonia evolved from ammonium ions reacting with hydroxide ions from the sodium hydroxide (see below).
| NH4+ (aq) + OH- → NH3 + H2O |
Ammonium Ions Hydroxide Ions
Test for Cu2+, Fe2+ and Fe3+
The test for Cu2+, Fe2+ and Fe3+
- Add aqueous sodium hydroxide
- Colour of precipitate is observed and recorded
Result and Equation:
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