# In a double displacement reaction, why don’t the two products reform after being dissolved in water? [duplicate]

Let’s say I have $$\ce{AB (aq) + CD (aq) —> AD + CB}$$. When AB and CD are dissolved in water, they get dissociated into their component ions. But why don’t they reform as AB and CD, if it is already known they (A and B, C and D) can form a chemical compound with each other? Why must the ions from each compound combine with ion(s) from the other compound?

By nature, dissociation in water causes ions from within an ionic compound to separate. When the ions are separated from their respective compounds, they are surrounded by water molecules to prevent them from recombining. But I’m guessing this blockage somehow doesn’t apply to to the relationship between the ions of different compounds.