Question

Beyond the differences in molecular mass, what is different about determining the molarity of a solution containing a salt versus a covalently linked molecule?

Answer 1

Molarity = mol per liter

many salts will dissociate in two ions, the cation and the anion, therefore they will interact between each other and will "appear" that there is a higher/lower concnetration of each, since it is the activity level they both interact.

For the covalent molecule, there is no dissociation, therefore, there is a "bulk" in solution.

The volume may be also changed with respect of the solution. Many solution will "shrink" and have smaller volumes that other solutions or even the pure solvent.