When ionic compounds dissolve/disassociate in water , they form (aqueous) solutions. if insoluble solid forms in water it is called a

Precipitate

When ionic compounds dissolve or disassociate in water, they form (aqueous) solutions and the dissolved substance is called the solute, whereas if insoluble solid forms in water it is called a PRECIPITATE. The term used to describe the emergence of the insoluble solid from solution is precipitation.

Because a model would make the investigation easier to understand