There are a lot of ways for finding the pH of something. One way is to use litmus paper. The pH paper is able to tell how strong the chemical is, whether it is a stronger acid or a stronger base. pH is a measure of the concentration of protons (H+) in a solution. Danish Bio-chemist Soren Peter Lauritz Sørensen introduced his concept in 1909. The p stands for the German potenz, meaning power or concentration, and the H for the hydrogen ion (H+).
The formula for calculating pH is: pH = - log [H+]
[H+] indicates the concentration of H+ ions (also written [H3O+], the equal concentration of hydronium ions), measured in moles per litre (also known as molarity).
Basic (Alkaline) substances have, instead of Hydrogen ions, a concentration of Hydroxide ions (OH-).
So, similarly the formula for calculating pOH is : pOH = - log [OH-]
The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 (10 times 10) more acidic than pH 6. The same holds true for pH values above 7, each of which is ten times more alkaline (another way to say basic) than the next lower whole value. For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 times 10) more alkaline than pH 8.
Pure water is neutral. But when chemicals are mixed with water, the mixture can become either acidic or basic. Examples of acidic substances are vinegar and lemon juice. Lye, milk of magnesia, and ammonia are examples of basic substances.
pH Logarithmic Scale