Define lattice energy in terms of the formation of an ionic compound.

Under standard conditions, the enthalpy change as gaseous ions come together to give one mole of the solid.

Define the enthalpy change of hydration.

The enthalpy change of hydration is the enthalpy change when one mole of gaseous ions is dissolved in sufficient water to form an infinitely dilute solution.

Are enthalpy of hydration values exothermic or endothermic, and why?

Enthalpy of hydration values are always exothermic (negative) because ion-dipole bonds form between ions and water molecules.

What type of bonding interaction is responsible for the exothermic nature of hydration?

Ion-dipole bonds form between the ions and polar water molecules.

Edexcel A-Level Chemistry 9CH0

Atomic Structure and the Periodic Table

Topic overview Protons, neutrons, electrons and isotopes Relative atomic mass and the mass spectrum Ionisation energy and the evidence for sub-shells Orbitals and electron configuration Periodicity across a period and down a group

Bonding and Structure

Topic overview Ionic bonding Covalent bonding, dative bonding and the shapes of molecules Electronegativity, polarity and intermolecular forces Structure and properties

Redox I

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Inorganic Chemistry and the Periodic Table

Topic overview Flame tests and how they work Thermal decomposition of nitrates and carbonates Carrying out flame tests and testing the gases Group 2 elements and their compounds Trends in Group 7 and predicting fluorine and astatine Halogen displacement reactions Disproportionation and the reactions of chlorine Halides with concentrated sulfuric acid, and the hydrogen halides Testing for halide ions with silver nitrate Testing for carbonate and hydrogencarbonate ions Testing for sulfate and ammonium ions

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Organic Chemistry I

Topic overview Formulae, homologous series and functional groups IUPAC nomenclature Types of organic reaction and structural isomerism Stereoisomerism and E/Z nomenclature Practical techniques in organic chemistry Alkanes, crude oil and combustion pollutants Radical substitution Alkenes, the double bond and hydrogenation Electrophilic addition, Markovnikov's rule and the test for an alkene Addition polymers and waste polymers Nucleophilic substitution of halogenoalkanes Rates of hydrolysis and the SN1 and SN2 mechanisms Classifying and oxidising alcohols Alcohols: practical techniques and the core practicals

Modern Analytical Techniques I

Topic overview Mass spectrometry Infrared spectroscopy and the characteristic absorptions Deducing functional groups from an infrared spectrum

Energetics I

Topic overview Enthalpy changes, standard definitions and calorimetry Hess's law and bond enthalpies

Kinetics I

Topic overview Collision theory and factors affecting rate Maxwell-Boltzmann distribution and temperature Catalysts, reaction profiles and measuring rate

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Energetics II

Topic overview Lattice energy Born-Haber cycles and electron affinity Entropy and the direction of change Gibbs free energy and thermodynamic feasibility

Redox II

Topic overview Standard electrode potentials and the hydrogen electrode Electrochemical cells, emf and cell diagrams Feasibility, the electrochemical series and disproportionation Storage cells, fuel cells and redox titrations

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Kinetics II

Topic overview Rate equations, orders and the rate constant Determining orders from experiments Rate-determining step and mechanisms Arrhenius equation and activation energy

Organic Chemistry II

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Organic Chemistry III

Topic overview The structure of benzene and the evidence for it Electrophilic substitution of benzene Nitration, halogenation, Friedel-Crafts and phenol Amines: structure and basicity Reactions of amines and preparing them Amides and condensation polymers Amino acids, zwitterions and proteins Empirical and molecular formulae from analytical data Grignard reagents and multi-step synthesis Purification techniques and the aspirin preparation

Modern Analytical Techniques II

Topic overview Carbon-13 and proton NMR Splitting, integration and the reference standard Chromatography High-resolution mass spectrometry

Energetics II

Lattice energy

3 things to know
Papers 1 and 3

Overview

The two definitions of lattice energy, enthalpy changes of hydration and of solution, how ionic charge and radius set the size of lattice and hydration enthalpies, calculating the enthalpy change of solution for sodium chloride and magnesium chloride, and measuring one in the laboratory.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why is the enthalpy of hydration of Al³⁺ more exothermic than that of Na⁺?

Key term

State the alternative definition of lattice energy involving the separation of ions.

Key term

When lattice energy is defined as the formation of a lattice from gaseous ions, is the value exothermic or endothermic?

Questions from this subtopic

Each one with the model answer underneath.

1
Define lattice energy in terms of the formation of an ionic compound.
Model answer
Under standard conditions, the enthalpy change as gaseous ions come together to give one mole of the solid.
2
State the alternative definition of lattice energy involving the separation of ions.
Model answer
The enthalpy change as one mole of the solid is broken up, its gaseous ions ending infinitely far apart.
3
When lattice energy is defined as the formation of a lattice from gaseous ions, is the value exothermic or endothermic?
Model answer
The value is always exothermic (negative).
4
Define the enthalpy change of hydration.
Model answer
The enthalpy change of hydration is the enthalpy change when one mole of gaseous ions is dissolved in sufficient water to form an infinitely dilute solution.
5
Are enthalpy of hydration values exothermic or endothermic, and why?
Model answer
Enthalpy of hydration values are always exothermic (negative) because ion-dipole bonds form between ions and water molecules.
6
What type of bonding interaction is responsible for the exothermic nature of hydration?
Model answer
Ion-dipole bonds form between the ions and polar water molecules.

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Atomic Structure and the Periodic Table

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Redox I

Inorganic Chemistry and the Periodic Table

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AAtomisation turns each element into gaseous atoms.

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