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Thermodynamics (AQA A Level Chemistry): Exam Questions

Exam code: 7405

4 hours31 questions

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Thermodynamics

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11 mark

Which of the following represents the second ionisation energy of strontium? 

  • Sr+ (s) → Sr2+ (aq) + e-

  • Sr (s) → Sr2+ (g) + 2e-

  • Sr+ (g) → Sr2+ (g) + e-

  • Sr (g) → Sr2+ (g) + 2e-

Choose your answer

21 mark

Ammonia is produced according to the following gas-phase synthesis:

                                                  N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

Thermodynamic data for the components of this equilibrium are:

Substance 

  N2 (g)

    H2 (g)

    NH3 (g) 

SӨ (J K-1 mol-1)

  191.5

   130.6

    192.5

The standard entropy change for this reaction is

  • -129.6 J K-1 mol-1

  • -198.3 J K-1 mol-1

  • 198.3 J K-1 mol-1

  • 514.6 J K-1 mol-1

Choose your answer

31 mark

Which of the following is the correct equation for Gibbs free energy?

  • ΔG = ΔH - TΔS

  • ΔG = ΔH + TΔS

  • ΔG = TΔS - ΔH

  • ΔG = ΔS + TΔH

Choose your answer

41 mark

The reaction between graphite and oxygen is as follows

                                   C (s) + O2 (g) → CO2 (g)           ΔHꝋf = -394 kJ mol-1

The entropy change for this reaction is (+)3 J K-1 mol-1. The free energy change for this reaction at 298 K is

  • -395 kJ mol-1

  • -1288 kJ mol-1

  • -500 kJ mol-1

  • 393 kJ mol-1

Choose your answer

51 mark

Which of the following best explains why lithium oxide has a much larger lattice enthalpy than potassium oxide?

  • Lithium ions have a greater charge than potassium ions

  • Potassium oxide has a greater Mr than lithium oxide

  • Potassium ions have a greater charge than lithium ions

  • Lithium ions have a smaller ionic radius than potassium ions

Choose your answer

61 mark

Which of the following represents the first electron affinity of oxygen?

  • O (g) + e- → O- (g)

  • 2O (g) + 2e- → 2O- (g)

  • O (g) + 2e- → O2- (g)

  • O- (g) → O (g) + e-

Choose your answer

11 mark

Ethene is produced according to the following gas-phase synthesis:

                                                 2C (s)  + 2H2 (g) → C2H4 (g) 

Thermodynamic data for the components of this equilibrium are

Substance             

  C (s)    

   H2 (g)    

   C2H4 (g)

ΔHϴf (kJ mol-1) 

    0

      0

       52

Sϴ (J K-1 mol-1)

    6

    131

      219

The free energy change for this reaction at 330 K is:

  • + 18202 kJ mol-1

  • + 33.83 kJ mol-1

  • + 70.15 kJ mol-1

  • -18098 kJ mol-1

Choose your answer

21 mark

Which of the following conditions will mean a reaction is never feasible?

 

    ΔH      

     ΔS  

Temperature

A

   Negative 

    Positive 

 High

  B  

Positive

    Negative

 High

C

 Negative

      Negative 

 Low

D

 Positive 

    Positive

   High

    Choose your answer

    31 mark

    Which of the following will show the least covalent character?

    • Beryllium bromide

    • Aluminium bromide

    • Potassium bromide

    • Magnesium bromide

    Choose your answer

    41 mark

    Thermodynamic data for the components for magnesium oxide are 

    Name of enthalpy change

    Energy change (kJ mol-1)

    Enthalpy of formation of magnesium oxide

    -602

    Enthalpy of atomisation of magnesium 

    +150

    First ionisation energy of magnesium  

    +738

    Second ionisation energy of magnesium  

    +1450

    Enthalpy of atomisation of oxygen

    +248

    First electron affinity of oxygen

    -142

    Second electron affinity of oxygen

    +844

    The lattice enthalpy of formation for magnesium oxide is:

    • -4174 kJ mol-1

    • -3890 kJ mol-1

    • -3766 kJ mol-1

    • -4138 kJ mol-1

    Choose your answer

    51 mark

    Using the information in the table to answer the question 

      Ion

          Value (kJ mol-1)

         ΔHӨlatt CaF2

    (+)2651

           ΔHӨhyd Ca2+ 

    -1616

         ΔHӨhyd F- 

    -504

    Which of the following is the correct value for the enthalpy change of solution, ΔHӨsol, of calcium fluoride, CaF2. 

    • +531 kJ mol-1

    • +5275 kJ mol-1

    • +27 kJ mol-1

    • -1589 kJ mol-1

    Choose your answer

    11 mark

    Which compound would have the greatest difference between the theoretical and experimental value for lattice enthalpy?

    • AgCl

    • AgI

    • NaF

    • NaCl

    Choose your answer

    21 mark

    Which row correctly describes a reaction that  is only feasible at a low temperature?

    • X (g) + Y (g) → Z (g)          exothermic

    • R (s) → T (g) + U (g)          endothermic

    • E (g) → 3F(g)          endothermic

    • M (g) + 2N (g) → P (g) + Q (g)          endothermic

    Choose your answer

    31 mark

    Use the data in the table to calculate the value of the first electron affinity of iodine

    Name of enthalpy change

    Energy change (kJ mol-1)

    Enthalpy of atomisation of calcium 

    +178

    1st ionisation energy of calcium

    +590

    2nd ionisation energy of calcium 

    +1145

    Enthalpy of atomisation of iodine

    +107

    Lattice energy of calcium iodide 

    -2074

    Enthalpy of formation of calcium iodide 

    -534

    • -294 kJ mol-1

    • -240 kJ mol-1

    • -480 kJ mol-1

    • -587 kJ mol-1

    Choose your answer

    41 mark

    Urea reacts with water to produce carbon dioxide and ammonia via the following reaction

    CO(NH2)2 (aq) + H2O (l) → CO2 (g) + 2NH3 (g)              ΔH = 133 kJ mol-1

    Thermodynamic data for the components of this reaction are

           Substance 

      CO(NH2)2 (aq)

       H2O (l)

        CO2 (g)

        NH3 (g)

         Sꝋ (J K-1 mol-1) 

                105

           70

         214

         192

    At which of the following temperatures will this reaction become feasible?

    • 0.31 K

    • 3.18 K

    • 132.6 K

    • 314 K

    Choose your answer

    51 mark

    Which of the following statements correctly explains the trend in enthalpy of hydration of the metal ions down Group 1?

    • The attraction between the ion and the hydrogen ions in water decreases down the group

    • The attraction the ion and the delta positive hydrogen atoms in water decreases down the group

    • The lone pair on the oxygen atom becomes more available for bonding

    • The attraction between the ion and the delta negative oxygen atoms in water decreases down the group

    Choose your answer