Some reactions of the halide ions
Cambridge A-Level Chemistry (9701) · Unit 11: Group 17 · 10 flashcards
Some reactions of the halide ions is topic 11.3 in the Cambridge A-Level Chemistry (9701) syllabus , positioned in Unit 11 — Group 17 , alongside The chemical properties of the halogen elements and the hydrogen halides and The reactions of chlorine. In one line: A white precipitate of silver chloride (AgCl) forms: Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 10 flashcards — 9 definitions and 1 key concept — covering the precise wording mark schemes reward. Use the 9 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Observed when aqueous silver nitrate is added to aqueous chloride ions
A white precipitate of silver chloride (AgCl) forms: Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
What the Cambridge 9701 syllabus says
Official 2025-2027 spec · AS LevelThese are the exact learning outcomes Cambridge sets for this topic. The candidate is expected to be able to do each of these on the relevant paper.
- describe the relative reactivity of halide ions as reducing agents
- describe and explain the reactions of halide ions with: (a) aqueous silver ions followed by aqueous ammonia (the formation and formula of the [Ag(NH3)2]+ complex is not required) (b) concentrated sulfuric acid, to include balanced chemical equations
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9701 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in Some reactions of the halide ions
- › Memorize the balanced equation for the decomposition of Group 2 nitrates: 2M(NO3)2 → 2MO + 4NO2 + O2.
- › Practice balancing equations for the thermal decomposition of Group 2 nitrates, ensuring the 2:2:4:1 molar ratio is maintained.
- › Distinguish between reactions that produce gas (like metals with acid) and those that simply dissolve to form a solution.
- › Apply the specific equation: 3Cl2 + 6NaOH → 5NaCl + NaClO3 + 3H2O to determine the correct molar yield of products.
- › Write out the full balanced equation for precipitation: Al2Cl6 + 6NaOH → 2Al(OH)3 + 6NaCl to find the correct molar ratio y/x.
Describe the trend in reducing ability of halide ions (Cl⁻, Br⁻, I⁻).
Reducing ability increases down the group (Cl⁻ < Br⁻ < I⁻). This is because the ions get larger and lose electrons more easily due to decreased attraction between the nucleus and the outer electron.
What is observed when aqueous silver nitrate is added to aqueous chloride ions?
A white precipitate of silver chloride (AgCl) forms: Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
What is observed when aqueous silver nitrate is added to aqueous bromide ions?
A cream precipitate of silver bromide (AgBr) forms: Ag⁺(aq) + Br⁻(aq) → AgBr(s).
What is observed when aqueous silver nitrate is added to aqueous iodide ions?
A yellow precipitate of silver iodide (AgI) forms: Ag⁺(aq) + I⁻(aq) → AgI(s).
How does the solubility of silver chloride (AgCl) change in dilute and concentrated ammonia?
AgCl dissolves in dilute ammonia solution. It also dissolves in concentrated ammonia solution to form a colourless solution.
How does the solubility of silver bromide (AgBr) change in dilute and concentrated ammonia?
AgBr is insoluble in dilute ammonia solution. It dissolves in concentrated ammonia solution to form a colourless solution.
How does the solubility of silver iodide (AgI) change in dilute and concentrated ammonia?
AgI is insoluble in both dilute and concentrated ammonia solutions.
Give the balanced chemical equation for the reaction of solid sodium bromide with concentrated sulfuric acid.
2NaBr(s) + 2H₂SO₄(l) → Na₂SO₄(s) + SO₂(g) + Br₂(l) + 2H₂O(l). Note: HBr is formed first, then oxidised to bromine by the sulfuric acid.
Give the balanced chemical equation for the reaction of solid sodium iodide with concentrated sulfuric acid.
8NaI(s) + 5H₂SO₄(l) → 4Na₂SO₄(s) + H₂S(g) + 4I₂(s) + 4H₂O(l). Note: Multiple reduction products of sulfuric acid are formed due to iodide's strong reducing power.
Give the balanced chemical equation for the reaction of solid sodium chloride with concentrated sulfuric acid.
NaCl(s) + H₂SO₄(l) → NaHSO₄(s) + HCl(g)
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Some reactions of the halide ions sits alongside these A-Level Chemistry decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
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