Question

What is the pH of a solution with a concentration of 1.0 * 10-4 M?

Answer 1

Answer: pH = 10

Explanation: First solve for pOH using the equation pOH=-log[OH-] = 4

Then plug the pOH in the equation, pH + pOH =14

then solve for pH. pH =14 - 4 = 10

Answer 2

Answer:

pH= 10

Explanation:

The pH really depends on what your solution is.

For example, if we are assuming that the concentration of 1.0M is of a strong monoprotic acid e.g. HCl, it would be safe to assume that almost all of the 1.0M acid has dissociated into its H+ ion, and its conjugate base. Thus, the pH can be determined by taking the negative log(to base 10), of the concentration.

Inversely, if the solution is of a strong base, the pOH value would be found, assuming the steps above. This pOH value can be used to infer a pH from the formula - pH + pOH = 14 then 14 - 4 = 10

Finally, come the weak acids/bases, which follow the rules above, except as they only partially dissociate, one needs its equilibrium constant to determine its extent of ionisation, to substitute into the negative log. This also is the case for the second, and higher order dissociation of polyprotic acids e.g. H2SO4.the answer is 10

Hope it helps