Syllabus Edition

First teaching 2023

First exams 2025

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The Chemical Properties of the Halogen Elements & the Hydrogen Halides (CIE AS Chemistry)

Exam Questions

46 mins13 questions
11 mark

What happens when iodine is bubbled through aqueous potassium bromide?

  • Iodine is oxidised to iodide ions.

  • Potassium bromide is reduced to bromine.

  • Bromide ions are oxidised to bromine.

  • No reaction occurs.

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21 mark

What happens when chlorine gas is bubbled through aqueous potassium iodide?

  • Iodide ions are oxidised to iodine.

  • Chlorine is oxidised to chlorate (V) ions.

  • Chlorine is oxidised to chloride ions.

  • There is no observable reaction.

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31 mark

When halogen sodium salts react with concentrated sulfuric acid which of the halide ions, chloride, bromide or iodide, acts as a reducing agent?

1

Cl

2

Br 

3

I

  • 1, 2 and 3

  • 1 and 2

  • 2 and 3

  • 1 only

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11 mark

On being heated, hydrogen iodide breaks down more quickly than hydrogen chloride.

Which statements does not explain this faster rate?

  • The breakdown of HCl is more exothermic than that of HI

  • The reaction of the breakdown of HI has smaller activation energy than that of HCl

  • The HCl bond is stronger than the HI bond

  • The HI bond is longer than the HCl bond

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21 mark

On contact with a hot glass rod, which gaseous hydride most readily decomposes into its elements?

  • Ammonia

  • Steam

  • Hydrogen iodide

  • Hydrogen chloride

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31 mark

When a hot platinum wire is plunged into a test tube of hydrogen chloride, no change occurs. However, if the experiment is repeated with hydrogen iodide, the gas is decomposed into its elements. 

Which factor does not result in this behaviour?

  • the strength of the hydrogen-halogen bond

  • the standard enthalpy of formation, ΔHfθ, of each of the products of decomposition

  • the electronegativity of the chlorine atom

  • the size of the halogen atom

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11 mark

X, Y and Z represent different halogens. The table shows the results of nine experiments in which aqueous solutions of X2, Y2 and Z2 were separately added to separate aqueous solutions containing X-, Y- and Z- ions.

 

X- (aq)

Y- (aq)

Z- (aq)

X2 (aq)

Y2 (aq)

Z2 (aq)

no reaction

X2 formed

X2 formed

no reaction

no reaction

no reaction

no reaction

Z2 formed

no reaction

What is the correct order to show the decreasing strength of the ions X-, Y- and Z-  as reducing agents?

  • X- > Y- > Z- 

  • X- > Z- > Y- 

  • Y- > Z- > X- 

  • Z- > X- > Y- 

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21 mark

A dark red/brown solution is formed when a halide salt containing the halide ion Y- reacts with aqueous chlorine. This solution then forms a violet solution when shaken with a cyclohexane solution.

What is halogen, Y?

  • Fluorine

  • Iodine

  • Iodide

  • Bromide

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31 mark

Which statement about Group 7 elements is not correct?

  • Fluorine is the weakest reducing agent in Group 7.

  • The bond dissociation energy of the hydrogen halides from HCl to HI increases.

  • CH3I would produce a silver halide precipitate with acidified AgNO3 faster than CH3Cl or CH3Br.

  • Astatine has a lower first ionisation energy than iodine.

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