A clear visual guide to the identification of three important gases: ammonia, hydrogen chloride and chlorine.

The resource uses step-by-step illustrated practical demonstrations to show students how each gas is tested and the chemistry behind the observations.

It covers:

Ammonia, NH₃ – produces white smoke of ammonium chloride with a glass rod wet with concentrated hydrochloric acid. An alternative test using damp red litmus paper is also shown.
Hydrogen chloride, HCl – appears as steamy fumes and produces white smoke of ammonium chloride when tested with a glass rod wet with concentrated ammonia.
Chlorine, Cl₂ – pale green chlorine gas turns damp blue litmus paper red before bleaching it white.

Relevant equations with state symbols are included, together with an explanation of the reaction of chlorine with water:

Cl₂(g) + H₂O(l) → HCl(aq) + HClO(aq)

The role of chloric(I) acid, HClO, as the bleaching agent is highlighted, helping students understand why damp indicator paper is first turned red and then bleached.

Safety information is included where appropriate, emphasising the need for these toxic and irritating gases to be handled using suitable laboratory precautions.

Designed as a concise classroom reference for GCSE, IGCSE and A-level Chemistry, the resource is suitable for practical preparation, teaching, revision or classroom display.

A QR code links students directly to FranklyChemistry, where the corresponding gas tests can be explored further.