Question

Which substance is an electrolyte: `O_2, C_3H_8, Xe`, or `KNO_3`?

Answer 1

In aqueous solution...........

Explanation:

In aqueous solution, a chemical reaction is conceived to occur for potassium nitrate:

`KNO_3(s) stackrel(H_2O)rarr K^+ + NO_3^(-)`

Charge separation occurs, as the water molecules bind to the anion, and to the cation.

Both the anion, and the cation are thus conceived to exist as their aquated ions, i.e. something of the sort, `[K(OH_2)_(4-6)]^+` and `[NO_3(H_2O)_(4-6)]^-`; this is what we mean when we write `KNO_3(aq)`; the ions exist in solution as `"aquated ions"`, i.e. loosely bound to several water molecules.

Because here, there is charge separation, a solution of potassium nitrate in water acts as an electrolyte.

On the other hand, dioxygen, xenon, and propane, are molecular species, which would have poor solubility in aqueous solution.