Why does the reducing power of halide ions increase going down Group 17?

Going down Group 17, the halide ions become larger . Their outermost electrons are further from the nucleus and experience more shielding . The electrons are held less tightly and are therefore more easily lost (donated) , increasing reducing power.

True or False? The addition of AgNO 3 to a solution containing I - ions gives a yellow precipitate.

True. Iodide ions form AgI , a yellow precipitate when silver nitrate solution is added. Chloride gives white (AgCl) and bromide gives cream (AgBr).

The silver halide precipitate that dissolves in .......... ammonia is AgCl, while AgBr only dissolves in .......... ammonia.

The silver halide precipitate that dissolves in dilute ammonia is AgCl, while AgBr only dissolves in concentrated ammonia.

Define reducing agent .

A reducing agent is a substance that donates electrons to another species, causing itself to be oxidised . In Group 17, halide ions are reducing agents, and their reducing power increases going down the group.

What observations are made when concentrated H 2 SO 4 is added to NaBr?

First, white fumes of HBr are produced. Then concentrated H 2 SO 4 oxidises HBr, producing reddish-brown fumes of Br 2 (g) and SO 2 (g): 2HBr (g) + H 2 SO 4 (aq) → Br 2 (g) + SO 2 (g) + 2H 2 O (l).

True or False? When concentrated H 2 SO 4 reacts with NaCl, the H 2 SO 4 is reduced to SO 2 .

False. With NaCl, concentrated H 2 SO 4 only produces HCl (g) (white fumes). The sulfuric acid is not reduced because HCl is not a strong enough reducing agent to reduce it. Only HBr and HI are strong enough to reduce H 2 SO 4 .

When concentrated H 2 SO 4 reacts with NaI, possible reduction products include SO 2 , .......... (yellow solid) and .......... (smell of bad eggs).

When concentrated H 2 SO 4 reacts with NaI, possible reduction products include SO 2 , S (yellow solid) and H 2 S (smell of bad eggs).

Write the ionic equation for the reaction of silver ions with iodide ions.

Ag + (aq) + I - (aq) → AgI (s) A yellow precipitate of silver iodide forms. Unlike AgCl and AgBr, AgI does not dissolve in either dilute or concentrated ammonia solution.

Describe the test for halide ions using silver nitrate solution, and explain why nitric acid is added first.

Nitric acid is added to remove any carbonate or sulfate ions that could also precipitate with Ag + . Silver nitrate solution is then added. A white (Cl - ), cream (Br - ) or yellow (I - ) precipitate of the silver halide confirms the halide present.

A LevelChemistryCambridge (CIE)Flashcards11. Group 17Some Reactions of the Halide Ions

Some Reactions of the Halide Ions (Cambridge (CIE) A Level Chemistry): Flashcards

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FrontReactions of the Halide Ions
Why does the reducing power of halide ions increase going down Group 17?

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Why does the reducing power of halide ions increase going down Group 17?
Going down Group 17, the halide ions become larger. Their outermost electrons are further from the nucleus and experience more shielding. The electrons are held less tightly and are therefore more easily lost (donated), increasing reducing power.
True or False?
The addition of AgNO₃ to a solution containing I^- ions gives a yellow precipitate.
True.
Iodide ions form AgI, a yellow precipitate when silver nitrate solution is added. Chloride gives white (AgCl) and bromide gives cream (AgBr).
The silver halide precipitate that dissolves in .......... ammonia is AgCl, while AgBr only dissolves in .......... ammonia.
The silver halide precipitate that dissolves in dilute ammonia is AgCl, while AgBr only dissolves in concentrated ammonia.
Define reducing agent.
A reducing agent is a substance that donates electrons to another species, causing itself to be oxidised. In Group 17, halide ions are reducing agents, and their reducing power increases going down the group.
What observations are made when concentrated H₂SO₄ is added to NaBr?
First, white fumes of HBr are produced. Then concentrated H₂SO₄ oxidises HBr, producing reddish-brown fumes of Br₂ (g) and SO₂ (g): 2HBr (g) + H₂SO₄ (aq) → Br₂ (g) + SO₂ (g) + 2H₂O (l).
True or False?
When concentrated H₂SO₄ reacts with NaCl, the H₂SO₄ is reduced to SO₂.
False.
With NaCl, concentrated H₂SO₄ only produces HCl (g) (white fumes). The sulfuric acid is not reduced because HCl is not a strong enough reducing agent to reduce it. Only HBr and HI are strong enough to reduce H₂SO₄.
When concentrated H₂SO₄ reacts with NaI, possible reduction products include SO₂, .......... (yellow solid) and .......... (smell of bad eggs).
When concentrated H₂SO₄ reacts with NaI, possible reduction products include SO₂, S (yellow solid) and H₂S (smell of bad eggs).
Write the ionic equation for the reaction of silver ions with iodide ions.
Ag⁺ (aq) + I^- (aq) → AgI (s)
A yellow precipitate of silver iodide forms. Unlike AgCl and AgBr, AgI does not dissolve in either dilute or concentrated ammonia solution.
Describe the test for halide ions using silver nitrate solution, and explain why nitric acid is added first.
Nitric acid is added to remove any carbonate or sulfate ions that could also precipitate with Ag⁺. Silver nitrate solution is then added. A white (Cl^-), cream (Br^-) or yellow (I^-) precipitate of the silver halide confirms the halide present.

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