Question 1

The bond enthalpy for the Cl-Cl bond is +243.0 kJ mol-1.

What is the enthalpy change of atomisation of chlorine in kJ mol-1?

  A  

+243.0

  B  

-243.0

  C  

+121.5

  D  

-121.5

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Question 2

The energy cycle for the dissolving of magnesium chloride in water is

The enthalpy of hydration of the magnesium ion is -1,920 kJ mol-1.

What is the enthalpy of hydration, in kJ mol-1, of the chloride ion?

  A  

-303 

  B  

-377

  C  

-606

  D  

-754

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Question 3

Which of these changes has the largest increase in the entropy of the system?

  A  

H2O(s) ➔ H2O(l)

  B  

Hg(l) ➔ Hg(g)

  C  

H2O(l) + HCl(g) ➔ H3O+(aq) + Cl-(aq)

  D  

C(graphite) ➔ C(diamond)

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Question 4

Energy is given out when one mole of gaseous magnesium ions is hydrated.

Mg2+(g) + aq ➔ Mg2+(aq)

This is more exothermic than the corresponding value for barium ions, Ba2+, because the

  A  

ionic radius of Mg2+ is less than that of Ba2+

  B  

ionisation energy of magnesium is greater than that of barium

  C  

lattice energy of magnesium oxide is more exothermic than that of barium oxide

  D  

solubility of magnesium hydroxide in water is less than that of barium hydroxide

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Question 5

Which change would have a negative ΔH value?

  A  

Cl(g) + e− ➔ Cl-(g)

  B  

Cl2(g) ➔ 2Cl(g)

  C  

Na(s) ➔ Na(l)

  D  

Na(g) ➔ Na+(g) + e-

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Question 6

Which pair of enthalpy changes will always share the same sign (i.e. both are always exothermic or both are always endothermic)?

  A  

enthalpy change of atomisation and enthalpy change of neutralisation

  B  

enthalpy change of atomisation and enthalpy change of solution

  C  

enthalpy change of combustion and enthalpy change of hydration

  D  

enthalpy change of solution and enthalpy change of hydration

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Question 7

Which of the following quantities, used in the calculation of the lattice energy of lithium oxide, Li2O, has a negative value?

  A  

the enthalpy change of atomisation of lithium

  B  

the first ionisation energy of lithium

  C  

the first electron affinity of oxygen

  D  

the second electron affinity of oxygen

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Question 8

Which of the equations below represents the first electron affinity for oxygen?

  A  

O2(g) + 2e- ➔ 2O-(g)

  B  

O2(g) - 2e- ➔ 2O-(g)

  C  

0.5O2(g) + e- ➔ O-(g)

  D  

O(g) + e- ➔ O-(g)

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Question 9

The ionic radii in nm of some ions are given below.

Which of the following compounds has the most exothermic lattice energy? They all have the same crystal structure.

  A  

LiF

  B  

LiCl

  C  

 CaO

  D  

CaS

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Question 10

Four changes W, X, Y and Z have the following signs for their ∆H and ∆sys S values.

Which of the following is a correct statement?

  A  

change W never occurs

  B  

change X could be the reaction of a solid carbonate with an acid

  C  

change Y could be a precipitation reaction

  D  

change Z could be the condensation of a gas to a liquid

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Question 11

The lattice enthalpy of calcium chloride can be calculated using three of the enthalpy changes below.

Which enthalpy change is not required?

  A  

enthalpy change of solution of calcium chloride

  B  

enthalpy change of hydration of Cl- ions

  C  

enthalpy change of formation of calcium chloride

  D  

enthalpy change of hydration of Ca2+ ions

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Question 12

The table below shows standard entropies, Sө.

What is the entropy change, ∆Sө, in J mol-1 K-1, for the following reaction?

CO(g) + 2H2(g) ➔ CH3OH(l)

  A  

-219.1

  B  

-88.5

  C  

+88.5

  D  

+219.1

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Question 13

Which equation represents the process that occurs when the standard enthalpy of atomisation of iodine is measured?

  A  

0.5I2(s) ➔ I(g)

  B  

I2(s) ➔ 2I(g)

  C  

0.5I2(g) ➔ I(g)

  D  

I2(g) ➔ 2I(g)

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Question 14

A reaction is exothermic and has a negative entropy change.

Which statement is correct?

  A  

the reaction is always feasible

  B  

the reaction is feasible above a certain temperature

  C  

the reaction is feasible below a certain temperature

  D  

the reaction is never feasible

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Question 15

Magnesium chloride, MgCl2, has two lattice energy values quoted in the data booklet.

The first is the experimental value, obtained from the Born-Haber cycle, -2,526 kJ mol-1; the second is the theoretical value, -2,326 kJ mol-1.

Why are the two values different?

  A  

the cation polarises the anion leading to some covalent bonding

  B  

the anion polarises the cation leading to some covalent bonding

  C  

magnesium chloride is a covalent substance

  D  

the results from the Born-Haber cycle are too inaccurate to be reliable

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