# Question 300fd

Apr 8, 2017

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.

${\text{NaOH"_ ((aq)) -> "Na"_ ((aq))^(+) + "OH}}_{\left(a q\right)}^{-}$

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, ${\text{H"_3"O}}^{+}$, i.e. a very high $\text{pH}$.

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.