AQA A-Level Chemistry 7405
Atomic Structure
Amount of Substance
Bonding
Energetics and Thermodynamics
Kinetics
Chemical Equilibria
Redox and Electrochemistry
Acids and Bases
Periodicity and Group Chemistry
Period 3 Elements and Their Oxides
Transition Metals
Introduction to Organic Chemistry
Hydrocarbons
Halogenoalkanes, Alcohols and Organic Analysis
Carbonyls, Carboxylic Acids and Derivatives
Aromatic Chemistry and Amines
Polymers, Amino Acids, Proteins and DNA
Organic Synthesis, NMR and Chromatography
Periodicity and Group Chemistry
Tests for Ammonium, Group 2, Hydroxide and Carbonate Ions
- 3 things to know
- Papers 1 and 3
Overview
The reagents, observations and equations for each of these tests.
What you need to know
Answer each one before you reveal it.
What reagent is added, and what is done, to test a solution for ammonium ions?
What gas is released when sodium hydroxide is warmed with a solution containing ammonium ions?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What reagent is added, and what is done, to test a solution for ammonium ions?
Model answer
Sodium hydroxide solution is added and the mixture is warmed gently.
- 2
What gas is released when sodium hydroxide is warmed with a solution containing ammonium ions?
Model answer
Ammonia gas (NH₃).
- 3
Write the ionic equation for the reaction that releases ammonia in the test for ammonium ions.
Model answer
NH₄⁺ + OH⁻ → NH₃ + H₂O.
- 4
How is the gas produced in the ammonium ion test identified?
Model answer
It turns damp red litmus paper blue (ammonia is alkaline) and has a pungent smell.
- 5
Why is the mixture warmed when testing for ammonium ions?
Model answer
Warming drives the ammonia gas out of solution so it can reach and turn the damp red litmus paper blue.
- 6
What reagent is used to identify Group 2 cations in a simple test-tube reaction?
Model answer
Sodium hydroxide solution.
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