What does it mean to be an electrolyte? An electrolyte is a substance that ionizes when dissolved in an
appropriate ionizing solvent, usually water. Electrolytes include most acid, bases, and salts. An
electrolyte will only conduct electricity when dissolved, for example…NaCl(aq) will conduct electricity
and is considered electrolytic, whereas NaCl(s) will not. NaCl is an ionic compound, and all ionic
compounds are polar, so as long as the ions are too strongly attracted to each other, the salt will be
considered soluble, the ions will dissociate (or separate), and the electrical current provided by the
battery now has a path to take through the solution and the circuit is complete. Okay, but looking at the
picture above, why doesn’t the lightbulb light up when sugar is dissolved in water? In the case of sugar
water, even though sugar is a polar molecule, when sugar dissolves, no ions are presents. This means
that there is no path for the electricity to take, and the circuit is not complete.
Make sense? Okay, now let’s take it a step further. Why is HCl(aq) considered an electrolyte? HCl is not
ionic, in fact, it is a molecular compound even though hydrogen ions (or hydronium ions) are free to
move around in solution when it is dissolved. So why is HCl considered molecular? A binary compound
is considered molecular if the bond between the two atoms is a covalent bond. In order to be
considered a covalent bond, the electronegativity different between the atoms in the bond must be less
than 2 and no metal can be present. The electronegativity difference between atoms determines how
polar the bond between those two atoms is.