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

Topic overview Oxidation numbers Oxidation, reduction, disproportionation and half-equations

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

Formulae, Equations and Amounts of Substance

Topic overview The mole, molar mass and empirical formula The ideal gas equation and molar volume Equations, concentration and reacting quantities Standard solutions, titration and uncertainty Percentage yield, atom economy and acid reactions Core practicals 1 to 3 Empirical formula and water of crystallisation by experiment Apparatus, uncertainty and mathematical skills

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

Equilibrium I

Topic overview Dynamic equilibrium and Le Chatelier's principle The equilibrium constant Kc

Equilibrium II

Topic overview Partial pressures and Kp Calculating Kp and the effect of conditions

Acid-Base Equilibria

Topic overview Bronsted-Lowry acids and bases, and the pH scale Strong and weak acids, Ka and Kw Calculating pH, and titration curves Buffer solutions and the Henderson-Hasselbalch equation Buffers in blood, and the core practical

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

Transition Metals

Topic overview Electron configuration and what makes a transition metal Complex ions, ligands and the colour of transition metal ions Coordination number, monodentate ligands and the shapes of complexes Bidentate and multidentate ligands, and ligand exchange Vanadium and chromium chemistry Reactions with sodium hydroxide and ammonia Cobalt and copper complexes Ligand exchange, amphoteric behaviour and the chelate effect Transition metals as catalysts

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

Topic overview Chirality Aldehydes, ketones and their oxidation Reduction and nucleophilic addition of HCN Testing for a carbonyl group: 2,4-DNPH and the iodoform reaction Carboxylic acids and their reactions Esters and acyl chlorides Reflux, extraction and recrystallisation Distillation, melting temperature and working safely

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

4 subtopics
12 things to know
Papers 1 and 3

What Energetics II covers

Covers lattice energy and the Born-Haber cycle, why theoretical and experimental values differ, entropy and the direction of change, and Gibbs free energy as the test of feasibility.

Where it is assessed

Papers 1 and 3

Advanced Inorganic and Physical Chemistry, then the synoptic paper.

Check the Pearson Edexcel specification ↗

The 4 subtopics

Each one has its own page.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

Which terms make up a Born-Haber cycle?

Process

What decides whether a reaction is thermodynamically feasible?

Key term

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

Numbers

State the equation that relates total entropy change to the entropy changes of the system and surroundings.

Numbers

State the equation for Gibbs free energy change.

Key term

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

Key term

Why is the first electron affinity of an element exothermic?

Key term

Give an example that shows enthalpy change alone cannot predict whether a reaction will occur.

Key term

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

Key term

Why is the second electron affinity of oxygen endothermic?

Key term

Define entropy.

Key term

What two factors together determine whether a reaction is thermodynamically feasible?

Take Energetics II further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

Enthalpy change vs Entropy change
Enthalpy change: heat transferred under constant pressure. Entropy change: change in dispersal of energy and particles.
Lattice formation enthalpy vs Lattice dissociation enthalpy
Lattice formation enthalpy: the enthalpy change when gaseous ions form one mole of an ionic solid. Lattice dissociation enthalpy: the enthalpy change when one mole of an ionic solid separates into gaseous ions.
Enthalpy of hydration vs Enthalpy of solution
Enthalpy of hydration: the enthalpy change when gaseous ions become aqueous. Enthalpy of solution: the enthalpy change when one mole of an ionic solid dissolves in water.

Questions from this topic

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

Bonding and Structure

Redox I

Inorganic Chemistry and the Periodic Table

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AAtomisation turns each element into gaseous atoms.

BIonisation energy removes electrons from the metal atoms.

CElectron affinity adds electrons to the non-metal atoms.

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Energetics II revision questions

What does Energetics II cover in Edexcel A-Level Chemistry?: 4 subtopics: lattice energy, born-haber cycles and electron affinity, entropy and the direction of change and gibbs free energy and thermodynamic feasibility. Each one has its own page with questions and model answers.
How is Energetics II organised?: By the Edexcel 9CH0 specification, subtopic by subtopic, so it matches the order you are taught it in.

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