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CAIE A-Level Chemistry 11.2 Halogens and Hydrogen Halides

Practise halogen oxidising-strength trends, reactions with hydrogen and the thermal stability of hydrogen halides.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • use the decreasing oxidising strength Cl2 > Br2 > I2 to predict halide displacement
  • describe reactions of halogens with hydrogen and compare their relative reactivity
  • explain decreasing hydrogen-halide thermal stability through weaker H–X bonds down the group

Covered syllabus points

11.2.1—Reactivity of the elements as oxidising agents11.2.2—Reactions of the elements with hydrogen11.2.3—Thermal stabilities of the hydrogen halides

11.2 The chemical properties of the halogen elements and the hydrogen halides question 1

[Maximum number: 3]

Chlorine is one of the elements in Group 17 of the Periodic Table.

Question (a)

(a)

Describe the relative reactivity of the elements chlorine to iodine as oxidising agents.

[ 1 ]

Question (b)

(b)

State what is observed when chlorine reacts with hydrogen.

[ 1 ]

Question (c)

(c)

Explain why the thermal stability of the hydrogen halides decreases down the group.

[ 1 ]

11.2 The chemical properties of the halogen elements and the hydrogen halides question 2

[Maximum number: 6]

The Group 17 elements are oxidising agents.

Question (a)

(a)

A student heats equal amounts of I2( g)\mathrm{I}_{2}(\mathrm{~g}) and H2( g)\mathrm{H}_{2}(\mathrm{~g}) in a sealed flask. The student leaves the contents to cool.

State what you would observe during the reaction.

[ 1 ]

Question (b)

(b)

Cl2\mathrm{Cl}_{2} and Br2\mathrm{Br}_{2} can each react with NH3\mathrm{NH}_{3} to give N2\mathrm{N}_{2} and a hydrogen halide, HX .

3X2+2NH3→ N2+6HX3 \mathrm{X}_{2}+2 \mathrm{NH}_{3} \rightarrow \mathrm{~N}_{2}+6 \mathrm{HX}

X = Cl or Br

The relative bond strengths of X-X and H-X determine the difference in enthalpy change of the two reactions.

[ 1 ]

Question (i)

(i)

Describe the relative thermal stabilities of HCl and HBr .

[ 1 ]

Question (c)

(c)

Table 1.2 shows some information about reactions of NaCl\ce{NaCl}, NaBr\ce{NaBr} and NaI\ce{NaI}.

Table 1.2

Table 1.2

[ 4 ]

Question (i)

(i)

Complete Table 1.2.

[ 4 ]
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