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A LevelChemistryCIEExam Questions2. Inorganic Chemistry2.3 Group 17

Group 17 (CIE A Level Chemistry)

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2.3 Group 17

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2.3 Group 17

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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

More than half a million tonnes of bromine is produced annually and is largely used for making other compounds. One important use of bromine is to manufacture agricultural chemicals.

What is another important use for bromine?

  • Flame-retardants and fire extinguishers

  • Water purification

  • Antiseptic agents

  • Bleaches for textiles and the paper industry

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31 mark

Chlorine is widely used in water treatment plants. Chlorine is reacted with water to produce hydrochloric acid and another chlorine-containing acid.

Which row correctly describes the properties of the reaction? 

 

Moles Cl2 used

Moles HCl produced

Other product formed

A

B

C

D

1

2

3

4

1

3

5

7

HClO

HClO2

HClO3

HClO4

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    41 mark

    The halogens exist as diatomic molecules, X2.

    Descending through Group 17 from chlorine to iodine the boiling points of the elements increase. 

    Which statement explains this trend?

    • Of the permanent dipole in the X2 molecule increases as the group is descended.

    • The X–X bond strength increases as the group is descended.

    • the electronegativity of X decreases as the group is descended.

    • The number of electrons in each X2 molecule increases as the group is descended.

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    51 mark

    How do the strengths of the forces between molecules, and the bonds within molecules, vary going down Group 17 from chlorine to bromine to iodine?

     

    Strength of van der Waals’ forces

    Strength of covalent bonds

    A

    B

    C

    D

    Increase 

    Decrease 

    Increase 

    Decrease 

    Increase

    Increase 

    Decrease

    Decrease

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      61 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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      71 mark

      A scientist compares the properties of chlorine, iodine and their compounds.

      Property X for iodine is bigger than for chlorine. 

      What is property X?

      • Solubility of the silver halide in NH3 (aq)

      • Oxidising ability of the element

      • Thermal stability of the hydrogen halide

      • Strength of van der Waals’ forces between the molecules of the element

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      81 mark

      Which properties of hydrogen halides steadily increase in the sequence HCl, HBr and HI?

      1

      Bond length 

      2

      Ease of oxidation

      3

      Thermal stability

      • 1 only

      • 1 and 2

      • 2 and 3

      • 1, 2 and 3

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      91 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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      101 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 factors result in this behaviour?

      1

      The strength of the hydrogen-halogen bond.

      2

      The standard enthalpy of formation, ΔHfo, of each of the products of decomposition.

      3

      The size of the halogen atom.

      • 1 only

      • 1 and 2

      • 2 and 3

      • 1, 2 and 3

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      11 mark

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

      Which statements explain this faster rate?

      1

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

      2

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

      3

      The HCl bond is stronger than the HI bond.

      • 1 only

      • 1 and 2

      • 2 and 3

      • 1, 2 and 3

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      21 mark

      The following report appeared in a newspaper:

      Barrels of bromine broke open after a vehicle collision on the motorway. Traffic was diverted as purple gaseous bromine drifted over the surface of the road (as bromine is more dense than air), causing irritation to drivers’ eyes. Firemen sprayed water over the scene of the accident, dissolving the bromine and washing it away.

      Which of the following observations is incorrect in the report?

      • Bromine is not purple

      • Bromine does not vaporise readily

      • Bromine is not denser than air

      • Bromine does not dissolve in water

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      31 mark

      What is the complete list of all the products from the reaction of potassium bromide with concentrated sulfuric acid?

      • Potassium hydrogen sulfate, hydrogen bromide, bromine, water and sulfur dioxide

      • Potassium hydrogen sulfate, hydrogen bromide, bromine and water

      • Potassium hydrogen sulfate, hydrogen bromide and bromine

      • Potassium hydrogen sulfate and hydrogen bromide

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      41 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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      51 mark

      What happens when chlorine is bubbled through an aqueous sodium hydroxide solution?

      1

      In hot NaOH (aq), ClO3– (aq) ions are formed.

      2

      In cold NaOH (aq), ClO– (aq) ions are formed.

      3

      Disproportionation of chlorine occurs in both cold and hot aqueous solutions.

      • 1 only

      • 1 and 2

      • 2 and 3

      • 1, 2 and 3

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      61 mark

      A molecule of chlorine has a relative molecular mass of 72.

      Which properties of the atoms in this molecule are the same?

      1

      Radius

      2

      Relative isotopic mass 

      3

      Nucleon number

      • 1 only

      • 1 and 2

      • 2 and 3

      • 1, 2 and 3

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      71 mark

      Astatine is the element below iodine in Group 17 of the Periodic Table.

      Which statement is most likely to be true for astatine?

      • Silver astatide reacts with dilute aqueous ammonia in excess to form a solution of a soluble complex.

      • Sodium astatide and hot concentrated sulfuric acid react to form astatine.

      • Astatine and aqueous potassium chloride react to form aqueous potassium astatide and chlorine.

      • Potassium astatide and hot dilute sulfuric acid react to form white fumes of only hydrogen astatide.

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      81 mark

      Which graph correctly illustrates a trend found in the halogen group?

      • 2-3-m-8a

      • 2-3-m-8b

      • 2-3-m-8c

      • 2-3-m-8d

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      91 mark

      When the yellow liquid NCl3 is stirred into aqueous sodium hydroxide, the reaction that occurs can be represented by the following equation.

      2NCl3 (l) + 6NaOH (aq) rightwards arrow N2 (g) + 3NaCl (aq) + 3NaOCl (aq) + 3H2O (l)

      What will be the result of this reaction?

      1

      A bleaching solution remains after the reaction.

      2

      The nitrogen is oxidised.

      3

      The final solution gives a precipitate with acidified silver nitrate.

      • 1, 2 and 3

      • 1 and 3

      • 2 and 3

      • 1 only

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      101 mark

      Compound X readily conducts electricity when added to water to produce a solution but does not conduct electricity in its liquid state.

      Which of the following could X be?

      1

      MgCl2

      2

      PCl3

      3

      SiCl4

      • 1, 2 and 3

      • 1 and 2

      • 2 and 3

      • 1 only

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      11 mark

      A student observed the reactions when sodium bromide and sodium fluoride were each reacted separately with concentrated sulfuric acid and concentrated phosphoric acid. 

      The observations are recorded in the table below.

       

      Sodium bromide

      Sodium fluoride

      Conc. H2SO4

      Conc. H3PO4

      Steamy fumes and brown vapour

      Colourless acidic gas formed

      Colourless acidic gas formed

      Colourless acidic gas formed

      Which deduction can be made from these observations?

      • Concentrated phosphoric acid is a stronger oxidising agent than concentrated sulfuric acid.

      • Concentrated phosphoric acid is a stronger oxidising agent than bromine.

      • Concentrated sulfuric acid is a stronger oxidising agent than fluorine.

      • Concentrated sulfuric acid is a stronger oxidising agent than bromine.

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      21 mark

      Iodine trichloride, ICl3, is made by reacting iodine with chlorine.

      I2 (s) + Cl2 (g) rightwards arrow 2ICl (s) ;    ∆Ho = +14 kJ mol–1

      ICl (s) + Cl2 (g) rightwards arrow ICl3 (s) ;   ∆Ho = –88 kJ mol–1

      By using the data above, what is the enthalpy change of the formation for solid iodine trichloride?

      • –162 kJ mol–1

      • –81 kJ mol–1

      • –74 kJ mol–1

      • –60 kJ mol–1

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      31 mark

      An unlabeled powder is known to be either a single sodium halide or a mixture of two different sodium halides. 

      To determine what the powder consists of a sample of the powder was first dissolved in water. Then acidified aqueous silver nitrate was added to the new solution, and a pale yellow precipitate was formed. When concentrated aqueous ammonia was added, the precipitate partly dissolved, leaving a darker yellow precipitate. 

      What might the powder have consisted of?

      • Sodium iodide only

      • Sodium bromide only

      • A mixture of sodium chloride and sodium bromide

      • A mixture of sodium chloride and sodium iodide

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      41 mark

      The following two experiments are carried out with anhydrous potassium chloride and observations X and Y are made at the end of each experiment. 

      The potassium chloride is dissolved in aqueous silver nitrate, and this is then added to aqueous ammonia- observation X. 

      Concentrated sulfuric acid is added to the potassium chloride, and the fumes produced are bubbled into aqueous potassium iodide solution - observation Y. 

      What are the observations X and Y?

       

      X

      Y

      A

      B

      C

      D

      Colourless solution

      Colourless solution

      White precipitate

      White precipitate

      Brown solution

      Colourless solution

      Brown solution

      Colourless solution

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        51 mark

        Element 85, astatine, is a halogen. If concentrated sulfuric acid is added to sodium astatide the resultant products are a mix of astatine, hydrogen astatide, hydrogen sulfide and sodium sulfate.

        Which product is formed by the oxidation of one of the constituents of sodium astatide?

        • Sodium sulfate

        • Hydrogen sulfide

        • Hydrogen astatide

        • Astatine

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        61 mark

        Q is a salt of one of the Group 17 elements chlorine, bromine, iodine, or astatine.

        The reaction scheme shows a series of reactions using a solution of Q as the starting reagent.

        RpZXjd2s_2-3-h-6

        What could Q be?

        • Sodium chloride

        • Sodium bromide

        • Potassium iodide

        • Potassium astatide

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        71 mark

        Two students, R and S, were asked to draw bar charts to represent how some properties of the halogens and their compounds differ in magnitude. Their diagrams are shown.

        2-3-cie-ial-chemistry-diagram-q7hard

        Which of the student’s diagrams are correct?

        • S only

        • R only

        • Both R and S

        • Neither R nor S

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        81 mark

        Solid potassium halides react with concentrated sulfuric acid, according to the following equations.

        Reaction 1:     2KCl + H2SO4 → K2SO4 + 2HCl

        Reaction 2:     2KBr  +  2H2SO4  →  K2SO4  +  SO2  +  Br2  +  2H2O

        Reaction 3:     8KI +  5H2SO4  →  4K2SO4  +  H2S  +  4I2  + 4H2O

        What is the largest change in the oxidation number of sulfur in each of these reactions?

         

        Reaction 1

        Reaction 2

        Reaction 3

        A

        B

        C

        D

        0

        0

        0

        0

        0

        2

        2

        4

        4

        4

        8

        8

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          91 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

          Which row in the following table contains the ions X-, Y- and Z-  in order of their decreasing strength as reducing agents?

           

          Strongest      rightwards arrow      Weakest           

          A

          B

          C

          D

          X-

          X-

          Y-

          Z-

          Y-

          Z-

          Z-

          X-

          Z-

          Y-

          X-

          Y-

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            101 mark

            Which row represents the correct electrodes used to manufacture chlorine from brine in a diaphragm cell?

             

            Nature of cathode

            Nature of anode

            A

            B

            C

            D

            Titanium

            Titanium

            Graphite

            Steel

            Graphite

            Steel

            Titanium

            Titanium

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