The table shows the values for all but one of the enthalpy changes relevant to this cycle. Enthalpy change Value/ kJ mol - 1 lattice energy - 2327 enthalpy change of hydration of Mg 2 + ion - 1920 enthalpy change of hydration of I - ion - 314 Define enthalpy change of hydration.

The enthalpy change of hydration is the enthalpy change when one mole of aqueous ions are formed from one mole of ions in the gaseous state. The enthalpy change of hydration is always exothermic.

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

MEDIUM

AS and A Level

IMPORTANT

Earn 100

Draw an energy cycle to show the dissolving of magnesium iodide in water.

Important Questions on 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 3

The table shows the values for all but one of the enthalpy changes relevant to this cycle.

Enthalpy change	Value/ $kJ {mol}^{- 1}$
lattice energy	$- 2327$
enthalpy change of hydration of ${Mg}^{2 +}$ ion	$- 1920$
enthalpy change of hydration of $I^{-}$ ion	$- 314$

Define enthalpy change of hydration.

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

The table shows the values for all but one of the enthalpy changes relevant to this cycle.

Enthalpy change	Value/ $kJ {mol}^{- 1}$
lattice energy	$- 2327$
enthalpy change of hydration of ${Mg}^{2 +}$ ion	$- 1920$
enthalpy change of hydration of $I^{-}$ ion	$- 314$

Use the values in the table to calculate the value for the enthalpy change of solution of magnesium iodide. (Only give the value without units)

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 3

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

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.

Draw an energy cycle to show the dissolving of magnesium iodide in water.

Important Questions on Lattice Energy

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