If the pH of a solution is 10.7, what would the pOH be?

2 Answers
Oct 6, 2016

3.3

Explanation:

Remember a simple thing that pH+pOH=14
so pOH= 14-10.7 = 3.3

Oct 6, 2016

pOH=3.3

Explanation:

2H_2O rightleftharpoons H_3O^+ +HO^-

At 298*K, we can write and quantify this equilibrium reaction:

K_w=[H_3O^+][HO^-]=10^-14

And taking log_10 of both sides:

logK_w=log_(10)[H_3O^+] +log_10[HO^-]=log_(10)10^-14

OR 14=-logK_w=-log_(10)[H_3O^+] -log_10[HO^-]

But, by definitions, pH=-log_(10)[H_3O^+], and pOH=-log_(10)[HO^-], and -logK_w=pK_w.

And thus, pK_w=14=pH+pOH.

Given your question (finally we've got to it!), pOH=14-pH = 14-10.7=?.