How do you find out the pH of sodium hydroxide?

Answer 1

Use the working definition of pH used in General Chemistry classes:

pH = -log([H+])

and the equilibrium constant for ionization of water:

[H+][OH-]=10-14

(Here [] denotes concentration in Molarity)

For moderate concentrations of NaOH (like 10-4-ish M and up, we can neglect the [OH-] from the actual ionization of water (since 10-7 is the maximum this concentration could be, when the NaOH concentration is 0, and even this is much less than the concentration of NaOH). Then we can say:

10-14=[H+][OH-]=[H+][NaOH] and then pH=-log[H+]=-log(10-14/[NaOH])

Just as an example, a 0.5 M solution has a pH of approximately -log(10-14/0.5) which is about 13

Answer 2

To find out the pH of sodium hydroxide, you can perform a pH test using a pH meter or pH paper. Sodium hydroxide is a strong base, so it will have a high pH value, usually around 12-14, depending on its concentration.