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International A Level (IAL)ChemistryEdexcelExam Questions2. Energetics, Group Chemistry, Halogenoalkanes & AlcoholsRedox Chemistry & Acid-Base Titrations

Redox Chemistry & Acid-Base Titrations (Edexcel International A Level (IAL) Chemistry): Exam Questions

Exam code: YCH11

44 mins18 questions

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Redox Chemistry & Acid-Base Titrations

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1
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What is the oxidation number of chromium in Na2Cr2O7?

  • +1

  • +2   

  • +3

  • +6

Choose your answer

2
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In an oxide of nitrogen, the oxidation number of nitrogen is +4.

Which is the formula of the oxide?

  • N2O

  • N2O3

  • N2O4

  • N2O5

Choose your answer

3
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What is the oxidation number of phosphorus in the phosphate ion, Pstraight O subscript 4 superscript 3 minus end superscript?

  • –3

  • +3

  • +5

  • +7

Choose your answer

11 mark

Hydrogen peroxide, H2O2, breaks down into water and oxygen.

In terms of oxidation and reduction, how do hydrogen and oxygen change in this reaction?

 

 

Hydrogen

Oxygen

☐

A

oxidised

reduced

☐

B

oxidised and reduced

unchanged

☐

C

reduced

oxidised

☐

D

unchanged

oxidised and reduced

    Choose your answer

    21 mark

    Iodate(V) ions, Ibegin mathsize 16px style O subscript 3 to the power of minus sign end style, oxidise dithionate ions, S2straight O subscript 6 superscript 2 minus end superscript, according to the equation

    x Ibegin mathsize 16px style O subscript 3 to the power of minus sign end style+ y S2straight O subscript 6 superscript 2 minus end superscript+ 4H2O → z Sbegin mathsize 16px style O subscript 4 to the power of 2 minus sign end style+ 8H++ I2

    What are the balancing numbers x, y and z?

     

     

    x

    y

    z

    ☐

    A

    2

    1

    2

    ☐

    B

    2

    2

    4

    ☐

    C

    2

    5

    5

    ☐

    D

    2

    5

    10

      Choose your answer

      31 mark

      Magnesium reacts with hydrochloric acid.

      Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)

      Which statement about this reaction is correct?

      • magnesium atoms act as oxidising agents

      • hydrogen molecules act as reducing agents

      • hydrogen ions act as oxidising agents

      • chloride ions act as oxidising agents

      Choose your answer

      4
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      The formulae of four ions are shown.

      Formula of ion

      CrO42-

      AlO2-

      [Fe(CN)6]4-

      [CrCl2(H2O)4]+

      How many of these ions contain a metal with an oxidation number of +3?

      • one

      • two

      • three

      • four

      Choose your answer

      5a1 mark

      This question is about the reaction shown.

      2KMnO4 + xH2C2O4 + yH2SO4 → 2MnSO4 + K2SO4 + 10CO2 + zH2O

      What values of x, y and z are needed to balance the equation?

       

       

      x

      y

      z

      ☐

      A

      5

      6

      8

      ☐

      B

      10

      3

      4

      ☐

      C

      5

      3

      8

      ☐

      D

      10

      6

      4

        Choose your answer

        5b
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        What is the reducing agent in the reaction?

        • H+

        • C2O42-

        • MnO4

        • SO4

        Choose your answer

        6
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        Which name is correct for the ion Sstraight O subscript 4 superscript 2 minus end superscript ?

        • sulfate(II)

        • sulfate(IV)

        • sulfate(VI)

        • sulfate(VIII)

        Choose your answer

        7
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        A diprotic acid, H2A, was titrated with sodium hydroxide solution.

        H2A (aq) + 2NaOH (aq) rightwards arrow Na2A (aq) + 2H2O (l)

        A 25.0 cm3 portion of 0.100 mol dm−3 sodium hydroxide solution required 12.80 cm3 of the solution of the diprotic acid for complete neutralisation. What is the concentration of H2A in mol dm−3?

        • 2.56 × 10−2

        • 9.77 × 10−2

        • 1.95 × 10−1

        • 3.91 × 10−1

        Choose your answer

        8
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        In which compound is the oxidation number of nitrogen +5?

        • Ca(NO3)2

        • Mg3N2

        • N2O3

        • NaNO2

        Choose your answer

        91 mark

        Which reaction is not a redox reaction?

        • 4KClO3 (s) → 3KClO4 (s) + KCl (s)

        • 2HCl (aq) + Ba(OH)2 (aq) → BaCl2 (aq) + 2H2O (l)

        • Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

        • Cl2 (g) + H2O (l) → HCl (aq) + HClO (aq)

        Choose your answer

        101 mark

        In which reaction is the copper species acting as an oxidising agent?

        •  Cu2+ + 2Ag → 2Ag+ + Cu

        • 2Cu++ O2– → Cu2O

        • 3Cu + O2 → Cu2O + CuO

        • Cu + Hg2+ → Hg + Cu2+

        Choose your answer

        11
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        Two half‐equations for a reaction are shown.

        Cu → Cu2+ + 2e−

        NO3− + 4H+ + 3e− → NO + 2H2O

        What is the overall ionic equation for this reaction?

        • Cu + Nstraight O subscript 3 superscript minus+ 4H+→ Cu2+ + NO + 2H2O

        • 2Cu + Nbegin mathsize 16px style O subscript 3 to the power of minus sign end style+ 4H+→ 2Cu2+ + NO + 2H2O

        • 3Cu + 2Nstraight O subscript 3 superscript minus+ 8H+→ 3Cu2+ + 2NO + 4H2O

        • 6Cu + 2Nstraight O subscript 3 superscript minus+ 8H+→ 6Cu2+ + 2NO + 4H2O

        Choose your answer

        12
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        A titre of 13.25 cm3 was obtained using a 50 cm3 burette.

        What is the percentage uncertainty in the titre?

        [Each reading of the burette has an uncertainty of ±0.05 cm3]

        • ±0.38%

        • ±0.75%

        • ±1.5%

        • ±7.5%

        Choose your answer

        13a
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        A pellet of sodium hydroxide has a mass of 0.700 g.

        Some pellets were dissolved to make 350 cm3 of 0.25 mol dm–3 solution.

        [Mr value: NaOH = 40]

        How many pellets were dissolved?

        • 4

        • 5

        • 8

        • 125

        Choose your answer

        13b
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        25.0 cm3 of the sodium hydroxide solution prepared in (a) was placed in a conical flask and titrated with sulfuric acid.

        2NaOH + H2SO4 → Na2SO4 + 2H2O

        Calculate the number of moles of sulfuric acid that reacted.

        • 0.0031

        • 0.0063

        • 0.013

        • 0.044

        Choose your answer

        13c1 mark

        Phenolphthalein indicator was used for the titration in (b). 

        What was the colour change at the endpoint?

        • colourless → pink

        • pink → colourless

        • orange → yellow

        • yellow → orange

        Choose your answer

        1a
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        A group of students carry out an experiment to find the concentration of chlorine, Cl2 (aq), in a solution.

        Excess potassium iodide solution is added to a 10.0 cm3 sample of the chlorine solution.

        Cl2 (aq) + 2I− (aq) rightwards arrow 2Cl− (aq) + I2 (aq)

        The iodine produced is titrated with a solution of thiosulfate ions of known concentration, using starch indicator.

        2S2O32- (aq) + I2 (aq) → S4O62- (aq) + 2I− (aq)

        The concentration of the Cl2 (aq) is between 0.038 and 0.042 mol dm−3 .

        What concentration of thiosulfate ions, in mol dm−3 , is required to give a titre of approximately 20 cm3 ?

        • 0.010

        • 0.020

        • 0.040

        • 0.080

        Choose your answer

        1b
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        What is the most suitable volume of 0.1 mol dm−3 potassium iodide solution, in cm3, to add to the 10.0 cm3 of chlorine solution?

        • 7.6

        • 8.0

        • 8.4

        • 10.0

        Choose your answer

        1c
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        What is the colour change at the end‐point of the titration?

        • colourless to pale yellow

        • pale yellow to colourless

        • colourless to blue‐black

        • blue‐black to colourless

        Choose your answer