How do you determine pH from molarity?

is also known as the concentration. The concentration can be converted to .

Take a sample of nitric acid ##"HNO"_3## with a molarity of ##"0.0032 M"##.

The molarity becomes the ##["H"^+]## concentration of ##3.2 xx 10^(-3)##.

We know this is the ##["H"^+]## concentration because ##"HNO"_3## is a strong acid, since the acid will completely dissociate into ##"H"^+## and ##"NO"_3^-##.

To find the ##"pH"## calculate ##- log["H"^+]##

##-log[3.2xx 10^(-3)] = 2.49 = "pH"##

To find the ##"pOH"## take the ##"pH"## value and subtract it from ##14##.

##14 - 2.49 = 11.51 = "pOH"##

To convert ##"pOH"## to ##["OH"^-]## calculate ##["OH"^-]=10^(-"pOH")##

##10^(-11.51)= 3.09 xx 10^(-12)=["OH"^-]##