Question

What is the pH of a 0.050 M NaOH solution?

Answer 1

The pH is about 12.7.

Explanation:

NaOH is a strong base, meaning it will dissociate basically completely in solution to form `Na^+` and `OH^-` ions in solution.

One mole of `OH^-` ions is created for every mole of NaOH that is dissolved. If it's a .05 M solution of NaOH, then it can also be interpreted to be a .05M solution of `OH^-`.

`pOH` (The pH scale for bases) can be found by taking the negative logarithm of `OH^-` concentration.

`pOH` = `-log[.05 M]` = 1.3.

However, we are trying to find `pH`, so we must use the formula
`pOH + pH = 14`.

Now that we know `pOH = 1.3`,
`pH = 14 - 1.3 = 12.7`.