What type of separation method would be best for isolating a soluble solid from a liquid?

The best method for isolating a soluble solid from a liquid is crystallisation. This process involves dissolving the solid in a solvent to form a solution and then slowly evaporating the solvent, allowing the solid to form crystals as it precipitates out of the solution. Crystallisation takes advantage of the fact that many solids are less soluble at lower temperatures, which means that as the solution cools or as evaporation occurs, the solute becomes supersaturated and crystals begin to form.

This method effectively separates the solid from the liquid while retaining the solid in its pure form, making it a preferred choice when purifying a soluble solid from a mixture. In contrast, evaporation is mainly used when you want to remove the solvent completely, and although it can be used to obtain solid from a solution, it does not ensure the formation of pure crystals. Filtration is suitable for separating insoluble solids from liquids rather than soluble solids, and dissolving is not a separation method but a process that creates a solution.