A-Level Chemistry CIE

Define the enthalpy change of atomisation, ΔH_at

The enthalpy change when 1 mole of gaseous atoms are formed from its element under standard condition.

Define lattice energy, ΔH_latt (the change from gas phase ions to solid lattice)

The energy change when anions and cations in the gaseous state condense to form 1 mole of an ionic solid.

Define the first electron affinity, EA

The enthalpy change when one mole of electrons are added to one mole of gaseous atoms to form one mole of gaseous ions under standard conditions.

What is enthalpy change ΔH?

The heat energy absorbed or released during a reaction at constant pressure.

Define the enthalpy change of hydration, ΔH_hyd

The enthalpy change when 1 mole of a gaseous ion dissolves in water completely.

Define the enthalpy change of solution, ΔH_sol

The amount of energy released when 1 mole of the ionic lattice dissolves in water to form a very dilute solution.

Define entropy, S

The number of possible arrangements of the particles and their energy in a given system.

State the Gibbs equation

ΔG^⦵ = ΔH^⦵ – TΔS^⦵

ΔG is Gibbs free energy change (kJ)

ΔH is enthalpy change (kJ/mol)

T is temperature (K)

ΔS is entropy change (kJK/mol)

Following the sign of ΔG^⦵ , when is a reaction or process feasible?

When the sign is negative.

Relationship between Faraday constant, Avogadro constant and the charge on an electron.

F = Le

Define standard electrode (reduction) potential

The potential difference of a half cell measured under standard conditions (1 M, 1 atm, 25°C) with a standard hydrogen electrode as the other half cell.

Define standard cell potential.

The potential difference measured across two half cells under standard conditions.

Define conjugate acid-base pairs.

Pairs of reactants and products linked together by the transfer of a proton.

Define mathematically pH

pH = -log[H⁺]

Define mathematically K_a

K_a = [H⁺] [A^-] / [HA]

HA is the weak acid

H⁺ is the hydrogen ions

A^- is the conjugate base

Define mathematically pK_a

pK_a = -log K_a

Define mathematically K_w

K_w = [H⁺] [OH^-]

Define a buffer solution

A mixture that resists a change in pH when a small amount of acid or alkali is added.

Define the partition coefficient, K_pc

The ratio of the concentrations of a solute in two different immiscible solvents in contact with each other when an equilibrium has been established.

Define a transition element

A d-block element which forms one or more stable ions with incomplete d orbitals.

Shape of the 3d_xy orbital

Shape of the 3d_z² orbital

Define ligand

A species that contains a lone pair of electrons that forms a dative covalent bond to a central metal atom/ion.

Define a complex

A molecule or ion formed by a central metal atom/ion surrounded by one or more ligands.

Define coordination number

Number of dative bonds between ligands and transition ion of a complex.

Define degenerate d-orbitals

When the orbitals of a subshell are all equal in energy.

Define non-degenerate d-orbitals

When d-orbitals experience an external force, they no longer remain at the same energy level.

Define the stability constant, K_stab, of a complex

The equilibrium constant for the formation of the complex ion in a solvent from its constituent ions or molecules.

Reactions by which halogenoarenes are produced

Substitution of an arene with Cl₂ or Br₂ in the presence of catalyst, AlCl₃ or AlBr₃ respectively.

Examples: benzene forms chlorobenzene

methyl benzene forms 2-chloromethylbenxene and 4-chloromethylbenzene

Reaction (reagents and conditions) by which phenol can be produced

1. phenylamine + HNO₂ or NaNO₂ and dilute acid

   temperature below 10℃

   produces diazonium salt

2. further warming of diazonium salt with H₂O

   gives phenol

Underlined are reagents

Italics are conditions

Chemistry of phenol with bases

will produce a salt

e.g. with NaOH(aq) to produce sodium phenoxide

Chemistry of phenol with Na(s)

produces sodium phenoxide and H₂(g)

Chemistry of phenol in NaOH(aq) with diazonium salts

Gives azo compounds

Chemistry of the nitration of phenol’s aromatic ring with dilute HNO₃(aq) at room temperature

gives a mixture of 2-nitrophenol and 4-nitrophenol

Bromination of phenol with Br₂(aq)

forms 2,4,6-tribromophenol

Where does the hydroxy group of a phenol direct incoming electrophiles to?

The 2-, 4-, 6- (ortho and para) positions

How is benzoic acid produced?

alkylbenzene + hot alkaline KMnO₄ + then dilute acid

example: methylbenzene to benzoic acid

How are esters produced?

alcohols + acyl chlorides

examples: formation of ethyl ethanoate and phenyl benzoate

What is the reaction (reagents and conditions) by which acyl chlorides can be produced?

carboxylic acids + PCl₃ and heat or PCl₅ or SOCl₂

What are the reagents and conditions to form primary and secondary amines from halogenoalkanes?

halogenoalkane + NH₃

in ethanol (as a solvent)

heated under pressure

Reagents and conditions to form secondary amines?

halogenoalkanes + primary amines in ethanol

heated in a sealed tube/under pressure

How are azo compounds used?

as dyes

Reagents in coupling reaction to form azo compound.

benzenediazonium chloride + phenol in NaOH (aq)

How are amides produced?

ammonia or primary amine

+ an acyl chloride

at room temperature

Which are weaker bases, amines or amides?

amides

The need for deuterated solvents when obtaining a proton NMR spectrum.

Contain deuterium not hydrogen, so no interference with the NMR.

What is the color and state of the complex:

pale blue solution

What is the color and state of the complex:

brown solution

What is the color and state of the complex:

blue ppt.

What is the color and state of the complex:

deep blue solution

What is the color and state of the complex:

yellow-green solution

What is the color and state of the complex:

pink solution

What is the color and state of the complex:

blue solution

What is the color and state of the complex:

blue ppt. slightly pinkish on browning