Home >> Science & Nature >> Science

How to Estimate the pH of a Solution

The pH of a solution indicates how acidic or basic it is. This value is of great importance in chemistry, medicine, natural sciences, nutrition and many other applications. You can estimate the pH of a solution if the concentrations of all the substances that constitute your solution are known. There are two ways to calculate pH. The first is to calculate the estimated concentration of hydrogen molecules (H+) and the second is to calculate the concentration of hydroxide molecules (OH-).

Things You'll Need

Calculator

Instructions

- 1
  Gather the known concentrations of the individual substances that make up your solution.
- 2
  Calculate the concentration of hydrogen ions (H+). Divide the number of hydrogen molecules by the volume of the solution. The negative log of this number is the pH reading. You should get a value between 0 and 14. For example, if the concentration of hydrogen is 0.01, the negative log (and therefore the pH) is 2.
- 3
  Calculate the concentration of hydroxide in your solution (pOH). Divide the number of hydroxide molecules by the volume of the solution. The negative log of this number is the pOH reading. You should get a value between 0 and 14. For example, if the OH- concentration is 0.00001, the negative log is 5. This is the pOH. To get the pH value, subtract this number from 14. In our example, 14 - 5=9. Your substance has a pH of 9.

Science