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Factors affecting the rate of nucleophilic substitution reactions15 September 2021

This page explains how the nature of the halogen, whether the halogenoalkane is primary, secondary or tertiary and the choice of solvent can all affect the rate of substitution reactions of halogenoalkanes... more

Advice to students (Paper 3) 15 September 2021

1. Revision. Go through the syllabus thoroughly for the option you have studied checking that you know and understand the chemistry given in the syllabus under 'Nature of Science', 'Understandings', 'Applications... more

Areas of difficulty 15 September 2021

I’ve been marking IB Chemistry papers now for a long time and there are several areas that every year many students seem to find particularly difficult. Some of these (such as hybridization) might be... more

Understanding hybridization 15 September 2021

The theory of hybridization is developed by first considering how atomic orbitals combine to form molecular orbitals which then leads on to how hybrid orbitals are formed. The relationships between shapes,... more

Using electrode potentials 15 September 2021

I think the main problem with questions involving oxidation and reduction and standard electrode potentials is that many teachers teach the cell convention – and many teach it wrongly. This can be seen... more

Understanding the activity series15 September 2021

There can be considerable confusion for standard level students over the position of certain metals in the activity series given in Section 25 the IB data booklet. One of the understandings in the IB... more

Manipulating equilibrium constants 15 September 2021

The importance of the relationship between the equilibrium constant and the balanced stoichiometric equilibrium reaction it relates to is stressed. What happens to the value of the equilibrium constant... more

Understanding and using ΔG 15 September 2021

ΔG is the change in free energy for a chemical reaction. If it is measured under standard conditions then it is known as the standard free energy change and has the symbol ΔG⦵. If the value of ΔG⦵... more

Shapes and hybridization 15 September 2021

Two related topics that students seem to find difficult are ‘Shapes of simple molecules and ions” and’ Hybridization’. Shapes of simple molecules and ions is covered using VSEPR theory for 2,... more

Advice to students (Paper 2) 15 September 2021

1. Revision. As for Paper 1 go through the syllabus thoroughly checking that you know and understand the chemistry given in the syllabus under 'NoS', 'Understandings', 'Applications and skills' and 'Guidance'... more