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When students have achieved a qualitative understanding of solubility equilibria they can use data from the Phet animation salts and solubility to calculate the value of a solubility product. The need to remember, however, that the animation provides information about the number of ions dissolved in solution but to calculate the solubility product they will need to work out the concentrations in mol dm^–3.

The steps students have to take to determine the solubility product of silver bromide using the Phet animation are listed in the following activity. You are asked to explain the purpose of each step.

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Why wasn't it necessary to calculate the number of moles of bromide ion in solution?

The number of moles of bromide ion is equal to the number of moles of silver ion that has already been calculated.

• Students can be given some ownership of their learning by letting them choose their own salt and its solubility product value using the 'Design a salt' tab in the Phet animation. They can make predictions about the properties of their salt and then check these using the animation. It can be very motivating for students to have some choice in the examples that they use.