NaOH(aq)NaOH(aq), KOH(aq)KOH(aq), Na_2CO_3(aq)Na2CO3(aq)
Water undergoes the following equilibrium.....the "autoprotolysis reaction"autoprotolysis reaction:
2H_2O(l) rightleftharpoonsH_3O^+ + HO^-2H2O(l)⇌H3O++HO−
And the given equilibrium has been precisely measured under standard conditions....
[H_3O^+][HO^-]=10^-14[H3O+][HO−]=10−14
If [HO^-]>10^-7*mol*L^-1[HO−]>10−7⋅mol⋅L−1, then the solution is basic.......and if [HO^-]<10^-7*mol*L^-1[HO−]<10−7⋅mol⋅L−1, then the solution is acidic.....
We can introduce the pHpH measurement by taking -log_10−log10 of both sides......[H_3O^+][HO^-]=10^-14[H3O+][HO−]=10−14
Thus -log_10[H_3O^+]-log_10[HO^-]=underbrace(-log_10(10^-14))_14
And thus our defining relationship, which you will use shortly.....
underbrace(-log_10[H_3O^+])_(pH)underbrace(-(log_10[HO^-]))_(pOH)=underbrace(-log_10(10^-14))_14
p H+ p OH = 14
So actual examples.....NaOH(aq), Na_2CO_3(aq), NH_3(aq), KOH(aq), NaF..........