The lattice energy of magnesium bromide, MgBr 2 can be calculated using the enthalpy changes shown in the table. Type of enthalpy change Value / kJ mol - 1 first ionisation energy of magnesium + 736 second ionisation energy of magnesium + 1450 first electron affinity of bromine - 325 enthalpy change of formation of MgBr 2 - 524 enthalpy change of atomisation of magnesium + 150 enthalpy change of atomisation of bromine + 112 State the meaning of the term lattice energy.

The energy given out when ions of opposite charges come together to form a crystalline lattice is called the lattice energy, ∆ H latt ⊝ .

The lattice energy of magnesium bromide, MgBr 2 can be calculated using the enthalpy changes shown in the table. Type of enthalpy change Value / kJ mol - 1 first ionisation energy of magnesium + 736 second ionisation energy of magnesium + 1450 first electron affinity of bromine - 325 enthalpy change of formation of MgBr 2 - 524 enthalpy change of atomisation of magnesium + 150 enthalpy change of atomisation of bromine + 112 State the meaning of the term second ionisation energy.

Second ionization energy is the energy required to remove the most loosely bound electron from a 1 + ion of an element. Due to the positive charge on the ion, the electrons are bound more strongly to the nucleus making the second ionization energy of an element always higher than the first.

The lattice energy of magnesium bromide, MgBr 2 can be calculated using the enthalpy changes shown in the table. Type of enthalpy change Value / kJ mol - 1 first ionisation energy of magnesium + 736 second ionisation energy of magnesium + 1450 first electron affinity of bromine - 325 enthalpy change of formation of MgBr 2 - 524 enthalpy change of atomisation of magnesium + 150 enthalpy change of atomisation of bromine + 112 Draw and label a Born-Haber cycle to calculate the lattice energy of magnesium bromide and calculate the lattice energy of magnesium bromide.

The Born-Haber cycle for magnesium bromide, MgBr 2 is: From the above energy cycle, the correct equations for the calculation of the lattice energy of magnesium bromide, MgBr 2 is: ∆ H latt ⊝ = ∆ H f ⊝ - ∆ H at ⊝ [ Mg ] + IE 1 [ Mg ] + IE 2 [ Mg ] + ∆ H at ⊝ [ Br ] + 2 EA 1 [ Br ] = - 524 - 150 + 736 + 1450 + 112 + 2 - 325 = - 524 - 1798 = - 2322 kJ mol - 1

EASY

AS and A Level

IMPORTANT

Earn 100

Draw a diagram to show how water molecules are arranged around a magnesium ion.

Important Questions on Lattice Energy

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 3

Explain why the enthalpy change of hydration of a magnesium ion is more exothermic than the enthalpy change of hydration of a sodium ion.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 4

The lattice energy of magnesium bromide, ${MgBr}_{2}$ can be calculated using the enthalpy changes shown in the table.

Type of enthalpy change	Value / $kJ {mol}^{- 1}$
first ionisation energy of magnesium	$+ 736$
second ionisation energy of magnesium	$+ 1450$
first electron affinity of bromine	$- 325$
enthalpy change of formation of ${MgBr}_{2}$	$- 524$
enthalpy change of atomisation of magnesium	$+ 150$
enthalpy change of atomisation of bromine	$+ 112$

State the meaning of the term lattice energy.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 4

The lattice energy of magnesium bromide, ${MgBr}_{2}$ can be calculated using the enthalpy changes shown in the table.

Type of enthalpy change	Value / $kJ {mol}^{- 1}$
first ionisation energy of magnesium	$+ 736$
second ionisation energy of magnesium	$+ 1450$
first electron affinity of bromine	$- 325$
enthalpy change of formation of ${MgBr}_{2}$	$- 524$
enthalpy change of atomisation of magnesium	$+ 150$
enthalpy change of atomisation of bromine	$+ 112$

State the meaning of the term second ionisation energy.

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 4

The lattice energy of magnesium bromide, ${MgBr}_{2}$ can be calculated using the enthalpy changes shown in the table.

Type of enthalpy change	Value / $kJ {mol}^{- 1}$
first ionisation energy of magnesium	$+ 736$
second ionisation energy of magnesium	$+ 1450$
first electron affinity of bromine	$- 325$
enthalpy change of formation of ${MgBr}_{2}$	$- 524$
enthalpy change of atomisation of magnesium	$+ 150$
enthalpy change of atomisation of bromine	$+ 112$

Draw and label a Born-Haber cycle to calculate the lattice energy of magnesium bromide and calculate the lattice energy of magnesium bromide.

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 5

For the pair $NaCl$ and $KBr$ , state with reasons, which one you would expect to have the higher lattice energy.

MEDIUM

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 5

For the pair $KCl$ and $SrS$ , state with reasons, which one you would expect to have the higher lattice energy.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 5

In some crystal lattices, some of the ions are polarised. State the meaning of the term ion polarisation.

EASY

AS and A Level

IMPORTANT

Chemistry for Cambridge International AS & A Level Coursebook with Digital Access (2 Years)>Chapter 19 - Lattice Energy>EXAM-STYLE QUESTIONS>Q 5

In some crystal lattices, some of the ions are polarised. Explain why a magnesium ion is better than a sodium ion at polarising an iodide ion.

Draw a diagram to show how water molecules are arranged around a magnesium ion.

Important Questions on Lattice Energy

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