This is an introduction to the pH scale.

Acids are chemical compounds that release hydrogen ions (H⁺) whenplaced in water.

pH is a measure of how acidic a solution is.


The concentration (M) of a solution is definedas the number of moles of solute divided by the volume of solution.

Molar concentration

On a simple level, the pH scalecan be viewed as a ranking ofthe number of hydrogen ionsin a solution.

pH can be expressed using the concentration of hydrogen ions, M

0.1 M

0.01 M

0.001 M

0.0001 M

M can be written in scientific notation

1 x 10⁻¹ M

1 x 10⁻² M

1 x 10⁻³ M

1 x 10⁻⁴ M

However, it would be easier to use the power instead

pH can be conveniently expressed as the positive exponent of the H⁺ ionconcentration.

You can see that the more acidic a solution is, the lower the pH

pH can be viewed as the power of hyrogen ion concentration