4.25 predict the effects of changing the pressure and temperature on the equilibrium position in reversible reactions.

If you move the equilibrium, you change the rate of reaction.
If the equilibrium moves to the right, you have more products. (the reactants are reacting faster)
If the equilibrium moves to the left, you have more reactants. (the products are reacting faster)

If you increase the pressure: the equilibrium will move to the side with least molecules.
If you decrease the pressure: the equilibrium will move to the side with the most molecules.

If you increase the temperature, there will be more products that are produced by an endothermic reaction.
This is because the reaction is trying to use up the extra heat, and it does so by putting the energy into making bonds.

4.24 understand the concept of dynamic equilibrium

Dynamic equilibrium is when a reversible reaction is happening both ways at the same time, at the same rate.

4.23 describe reversible reactions such as the dehydration of hydrated copper(II) sulfate and the effect of heat on ammonium chloride

If you add water to copper sulphate you can make hydrated copper sulphate.
If you remover the water from hydrated copper sulphate you can make copper sulphate.

When heated, ammonium chloride splits into to hydrogen chloride and ammonia.
Hydrogen chloride and ammonia can be reacted to make ammonium chloride.

4.22 understand that some reactions are reversible and are indicated by the symbol ⇌ in equations

Some reactions can happen both ways: the reactants can make the products and the products can make the reactants.

This symbol shows that ⇌.