Understanding pH

* pH is a measure of the acidity or alkalinity of a solution.

* A lower pH indicates a more acidic solution.

* A higher pH indicates a more alkaline (basic) solution.

* The pH scale is logarithmic, meaning each whole number change represents a tenfold difference in acidity.

Calculation

* Difference in pH: The difference in pH between 4 and 6 is 2.

* Tenfold difference: Since the pH scale is logarithmic, a difference of 2 means the solution with pH 4 is 100 times more acidic than the solution with pH 6.

Explanation

Think of it this way:

* pH 6 is 10 times less acidic than pH 5.

* pH 5 is 10 times less acidic than pH 4.

Therefore, pH 4 is 10 x 10 = 100 times more acidic than pH 6.