Calculate the ["H"_3"O"^(+)] and ["OH"^(-)] for 0.00024 M NaOH. Answer in units of M?

1 Answer
May 15, 2018

Begin by recognizing that "NaOH" is a strong base, which dissociates completely in water.

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

Therefore, given "0.00024 M NaOH", since ["OH"^(-)] = ["NaOH"], what is the concentration of "OH"^(-)?

At 25^@ "C", for the autodissociation of water,

2"H"_2"O"(l) rightleftharpoons "H"_3"O"^(+)(aq) + "OH"^(-)(aq)

K_w = ["H"_3"O"^(+)]["OH"^(-)] = 10^(-14)

So,

["H"_3"O"^(+)] = K_w/(["OH"^(-)]) = ???