CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Qualitative Tests
Chemical tests for the gases
- 3 things to know
- Unit AS 1
Overview
Test for hydrogen gas and the result, test for oxygen gas and the result and test for chlorine gas and the result.
What you need to know
Answer each one before you reveal it.
Why does chlorine both redden and bleach damp litmus paper?
Describe the test for hydrogen gas and the result.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe the test for hydrogen gas and the result.
Model answer
A lighted splint is held at the mouth of the tube and the gas burns with a squeaky pop.
- 2
Describe the test for oxygen gas and the result.
Model answer
A glowing splint is held in the gas and it relights.
- 3
Describe the test for chlorine gas and the result.
Model answer
Damp blue litmus paper is held in the gas, and it turns red and is then bleached white.
- 4
Why does chlorine both redden and bleach damp litmus paper?
Model answer
Chlorine reacts with the water on the paper to give an acidic solution, which reddens the litmus, and the chlorate(I) formed then oxidises the dye and removes the colour.
- 5
Describe the test for carbon dioxide and the result.
Model answer
The gas is bubbled through limewater, which turns milky.
- 6
Write the equation for the reaction of carbon dioxide with limewater.
Model answer
The equation is Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l).
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