When measuring the pH of any substance you are measuring the concentration of what element?

Answer 1

pH is the measure of the concentration of hydrogen ions, which are in fact protons (although it is debatable as to whether they should be considered as hydrogen ions or hydronium ions (H3O+ i.e. a water molecule that has picked up a proton).

It is measured on a logarithmic scale, and pH is defined as -log[H+].

[] indicate concentration.

Logarithm is base 10.

Lower pH actually means higher concentration of protons because of how the function written above works. The concentration is usually written in scientific notation, and the exponent on the 10 is frequently negative. A larger negative exponent (10^-12) is indicative of a smaller concentration than a less negative exponent (10^-3). The negative sign in front of the logarithm makes (most) pH readings positive, and thus the smaller the pH the more H+ ions, and the more acidic.

Answer 2

When measuring the pH of a substance, you are measuring the concentration of hydrogen ions (H+). The pH scale indicates the acidity or basicity of a solution based on the concentration of these hydrogen ions.