The concentration of free protons [H+] directly correlates with the strength of an acid.
—Log Proton Concentration [pH]
|Substance||[H+] concentration||scientific notation||pH|
What if you know the pH of a substance, and want to know how that translates to proton concentration?
Knowing this, you can simply plug in your pH as your Y value, allowing X to represent your proton concentration.
Using pure water (pH=7), let’s first take the log positive by shifting the negative to the other side of the equation:
Having done, that, we can simply follow the “if log X = Y, then X = 10Y” logic:
Thus, having run the calculation in reverse, we know that if pure water has a pH of 7, then its proton concentration must be 1x10-7 M.
Another way to calculate pH, which is especially useful for buffer solutions: