What is an example of a pH practice problem?

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Answer 1 · 2014-06-15T16:23:08

Generally, most pH problems ask you to determine pH from $[H^+]$ the hydrogen ion concentration,or conversely, determine the $[H^+]$ from the pH.

Let's look at the strong acid HCl, hydrochloride acid, which has a concentration of 0.1 molar.

In aqueous solutions, hydrochloric acid dissociates into hydrogen and chloride ions.

HCl $->$ $H^+$ + $Cl^-$

Because there is a one to one ratio between the acid and the hydrogen ion, the $[H^+]$ is 0.1 molar.

Now convert the hydrogen ion concentration to pH using the equation pH = -log $[H^+]$

Applying this to our problem

pH = -log $[H^+]$
pH = -log [0.1]
pH = 1

To reverse the problem from pH to [H+]
Use the equation
[H+] = antilog(-pH)