If you are working in a chemical or other scientific laboratory, you may need to use a pH meter to find the
solution is acidic or basic.
When pH or pOH of solution is known, we can readily calculate concentrations of hydronium ion
(H_{3}O^{+}) or hydroxyl ion (OH^{-}) using the pH equation. Also, in this online pH calculator,
you have to just substitute pH or pOH value and it will give you what is the H_{3}O^{+} ion concentration of
aqueous solution. Also, several examples are explained with each step of calculation at the end of this tutorial.

Sometimes, H_{3}O^{+} is denoted as H^{+} and we also use H^{+} term instead of H_{3}O^{+} term.

There are two calculators in this online calculator.

- Calculator of pH to H
^{+}concentration - Calculator of pOH to H
^{+}and OH^{-}concentration

This calculator will give H^{+} concentration in mol dm^{-3}. Ionic product (K_{w} value) of water is taken as 1 * 10^{-14}
mol^{2} dm^{-6}. Therefore, results of this online calculator are very much accurate around 25^{0}C.

Answer

- If you see 'e' in the answer take e = 10, as an example if answer is given as 1e-7, it means 1 * 10
^{-7} - If answer is given as 1.00005e-5, 1.00005e-5 = 1.00005 * 10
^{-5}

This calculator will give H^{+} concentration in mol dm^{-3}. Here also, results of this online
calculator are very much accurate around 25^{0}C.

Answer

Because pH = 1, this solution is a strong acidic solution. We can substitute pH = 1 in pH equation.

- pH = -log[H
^{+}] - 1 = -log[H
^{+}] - [H
^{+}] = 0.1 mol dm^{-3}

Because pH = 13, this solution is a strong basic solution. We can substitute pH = 1 in pH equation.

- pH = -log[H
^{+}] - 13 = -log[H
^{+}] - [H
^{+}] = 1 * 10^{-13}mol dm^{-3}

Because pH + pOH = 14 at 25^{0}C.

- pH + pOH = 14
- 13 + pOH = 14
- pOH = 13

From pOH equation, OH^{-} concentration can be calculated.

- pOH = -log[OH
^{-}] - 1 = -log[OH
^{-}] - [OH
^{-}] = 0.1 mol dm^{-3}

Because pH value is given, we can find the H^{+} concentration directly from pH equation.

- pH = -log[H
^{+}] - 3 = -log[H
^{+}] - [H
^{+}] = 1 * 10^{-3}mol dm^{-3}

Whether acetic acid concentration is given, we cannot get a direct and
easy relationship between acetic acid concentration
and H^{+} ion concentration because acetic acid is a weak acid.

In the answer too, you can see **H ^{+} ion concentration is much lower than acetic acid concentration**.

Questions

In some chemistry application, pH values will be given to maintain conditions of different processes. In such cases, it is essential to calculate concentrations of chemicals in such situatins. The, we can do a calculation based on the given pH value. Because we can convert pH value to H^{+} ion concentration and can continue the calcuation to calculate concentrations of other chemicals. Some examples are given below.

- Preparing acetic acid solution which has a pH value of 3

If there are two or more acids in a aqueous solution, all of them give H^{+} ions in different amounts (or in concentrations).
So, there is only one H^{+} ion concentration throughout the aqueous solution. So, pH value is uniform throughout the solution.
When, we measure the pH value of acidic solution and calculate H^{+} ion concentration, it indicates the overall H^{+}
concentration of solution. But, you cannot decide individual concentrations of HCl and H_{2}SO_{4} acids.

See pH equation. There are only 2 terms in pH equation, H^{} ion concentration and pH value. There is no term for temperature. So, there is no effect for H^{+} ion concentration when it is calculated from pH value in different temperatures.

pH to pOH calculator
Graph between H^{+} ion and pH
pH of HCl solution
pH calculator for H_{2}SO_{4} acid
pH of KOH solution | Online calculator
Is barium hydroxide a strong base?

Titration curves of NaOH and HCl titration
Titration classifications, standard solutions, equivalence point
How to decide limiting reagent in chemical calculations
Online pH calculator for weak acids
Dissociation of weak acids and how to calculate pH
How to calculate pH or pOH in NaOH and H_{2}SO_{4} reaction solution
pH of nitric acid solution