Question

Question #300fd

Answer 1

Because it ionizes completely in aqueous solution.

Explanation:

Sodium hydroxide is a strong base because it ionizes completely when dissolved in water, i.e. for every mole of sodium hydroxide that you dissolve you get `1` mole of hydroxide anions.

`"NaOH"_ ((aq)) -> "Na"_ ((aq))^(+) + "OH"_ ((aq))^(-)`

This means that sodium hydroxide solutions have a very high concentration of hydroxide anions, which, in turn, implies a very low concentration of hydronium cations, `"H"_3"O"^(+)`, i.e. a very high `"pH"`.

So, we consider sodium hydroxide a strong base because this compound is `100%` dissociated in aqueous solution, i.e. sodium hydroxide exists as ions when dissolved in water.