Question

What is the hydrogen ion and hydroxide ion concentration for a pOH of 6.840? Is the solution an acid or a base

Answer 1

To solve the problem you need to use the following formulas to determine the pH and the pOH.

1) pH=−log[H3O+]

2) pOH=−log[OH−]

3) 14.00=pH+pOH

Given that the pOH is 6.840 the pH will be

pH=14.00-6.840=7.160

To determine the concentrations we need to solve equations 1) and 2). This gives us

$[H_3O^+]=10^{-pH}$$[OH^-]=10^{-pOH}$

Solving using the pH and pOH values

$[H_3O^+]=10^{-7.16}=6.9183\times10^{-8}\text{ M}$$[OH^-]=10^{-6.84}=1.4454\text{ }\times10^{-7}\text{ M}$