Question

Question #49968

Answer 1

`4` moles of ions.

Explanation:

The trick here is to realize that potassium nitrate, `"KNO"_3`, is soluble in water, which implies that it dissociates completely in aqueous solution to produce potassium cations and nitrate anions.

`"KNO"_ (3(aq)) -> "K"_ ((aq))^(+) + "NO"_ (3(aq))^(-)`

As you can see, for every `1` mole of potassium nitrate that dissociates, you get `1` mole of potassium cations and `1` mole of nitrate anions.

This means that when you dissolve `2` moles of potassium nitrate in enough water, your solution will contain

`2 color(red)(cancel(color(black)("moles KNO"_3))) * "2 moles ions"/(1color(red)(cancel(color(black)("mole KNO"_3)))) = "4 moles ions"`

A solute that produces `2` moles of particles of solute, which in this case are ions, for every `1` mole of solute dissolved to make the solution is said to havea van't Hoff factor equal to `2`.

If you want the actual number of ions formed in the solution, use the fact that `1` mole of ions contains `6.022 * 10^(23)` ions `->` this is known as Avogadro's constant, `N_"A"`.

So in your case, the number of ions produced in the solution would be equal to `4 * N_"A"`.