What does the pH scale measure?
It is a measure of the concentration of hydronium ion....
In aqueous solution under standard conditions,
And so in aqueous solution....
And why do we use such a scale? Well, logarithms are a throwback to the days BEFORE ready access to electronic calculators....for scientists, and engineers, and for accountants and actuaries...when they were faced with large and small division and multiplication, and calculation of compound interest … it was EASIER to do addition i.e.