Acids and Bases
When ionic compounds dissolve in water, their ions separate from one another in a process called dissociation. One interesting feature of water and many other covalent compounds is that they too can dissociate into ions.
What types of compounds dissociate in water?
Many 'covalent' molecules do dissociate in water, HCl (as pointed out in the comments), phenol, acetic acid, for example, whereas some 'ionic' compounds do not to any appreciable extent, e.g. silver chloride, lead sulfate.
What will completely dissociate in water?
For all practical purposes, strong acids completely dissociate in water. That is the definition: A strong acid is an acid that completely dissociates in water. We see that the position of equilibrium lies far to the right.
