markscheme answer

Compare the relative acidities of propanoic acid, propan-1-ol, and phenol

Propanol OH bond is strengthened by positive inductive effect of alkyl group

Phenol phenoxide ion is stabilised by delocalisation of oxygen lone pair into ring

Propanoic acid propanoate ion stabilised delocalisation of negative change by carbonyl bond

How can temperature be controlled in an experiment?

Use a thermostatically controlled water bath

How can you ensure results are reliable?

Repeat the experiment until the results are consistent

Define the term rate of reaction

How the concentration of reactants change over time

Why might it be difficult to see whether a thermal decomposition reaction of carbonate compound has taken place in an often test tube

Gas produced is colourless

The solid remains white

State what is meant by the term stability constant

Equilibrium constant for the formation of complex ion in solution

Describe how the results of an experiment can be used to confirm that the reaction is first first-order with respect to X

Half life remains constant

Plot [X] against time

Why is the enthalpy change of hydration more exothermic for br- than i-

Ionic radius is smaller

Stronger ion-dipole attractions with water

State and explain the relative rates of hydrolysis of chloroalkane, acyl chloride, and chlorobenzene

In acyl chloride c-cl bond as it is electrons deficient due to oxygen atom

In chloralkane, c-cl bond is strengthened by positive inductive effect

In chlorobenzene, the c-cl bond is part of the delocalised system

Explain why polyamides normally biodegrade more readily than poly alkenes

C-c bonds are non polar so polyamides can be hydrolysed

Why is the first electron affinity exothermic

Attraction between the nucleus and electron

Why is 2nd electron affinity endothermic?

Due to repulsion between the 1- ion and electron

Define lattice energy

When one mole of a solid ionic compound is formed form its constituent ions in the gaseous state

Why is a complex colourless?

The d-subshell is full for the ion therefore no d electrons are promoted

Define conjugate acid base pair

Pair that differ by the presence or absence of a hydrogen ion

Explain why benzamide is a much weaker base than ammonia

The lone pair on the nitrogen overlaps and is incorporated with the ring

This increases the electron density of the ring