Posted by Tarkan on .
What will be the pH of an aqueous solution containing 0.040 mol/L sodium hydroxide??
I got 1.40 or 1.398 I rounded the numbers is
my answer right??? If not what's the right answer??
I know I wrote the question again, because on the previous answer I did not understand what u mean and from where u got 14.00 ... Plz can u explain it again so that I get it . It's very important to me thank u :)

Chemistry 
DrBob222,
NaOH ==> Na^+ + OH^
NaOH is 0.04M from the problem.
Na^+ is 0.04M and OH^ is 0.04M
You took the log(OH^), which is 1.40 and you called that the H^+ but it isn't. It is the (OH^) so you calculated the pOH and not the pH. But you can convert your pOH to pH from the equation
pH + pOH = pKw = 14.00
pH + 1.40 = 14.00
pH = 14.00  1.40 = 12.60