What Is The PH Scale?

The pH scale shows the alkalinity or acidity of a substance.  7 is neutral.  From 7, as the numbers get lower, the substance is more acid.  From 7, as the numbers get higher, the substance is more alkaline.  You can use litmus paper to test for acid or alkali.

The pH scale is a measurement of how acidic a solution is or how alkaline it is. It has a range of 14 units, which pH 1 being the most acidic and pH 14 being the most alkaline. Common acids include vinegar and lemon juice, which are about pH 3; common alkalis include sodium bicarbonate, which is about pH 11.

A pH of below 6 is regarded as acid with 6 being a very weak acid and pH 1 being the strongest acid. This is the pH of something like hydrochloric acid. A pH of around 7 (6 to 8) is regarded as neutral – this is the pH of ordinary tap water. A pH of 8-14 is regarded as alkaline with pH 14 being the pH of a very concentrated solution of sodium hydroxide.

The pH of a solution can be measured on the pH scale using indicators. These include litmus, which can be impregnated into paper, giving an easily dip reaction. The paper changes colour and this can then be compared with the colours on a known pH scale.

I agree with the above comment about the pH below would be an acid, 7 being a neutral pH, and anything greater than 7 alkaline or basic. What I would like to share is what does pH really mean using the pH and a hypothetical HCl solution with a concentration of 1 x 10 -3 M HCl solution.

pH = -log[H+] so the concentration depends on the amount of free protons in aqueous(water) solution.

Using the equation: - log [1 x 10-3M] and the concentration of the solution .

you get  pH = 3   definitely acidic, lower than pH of 7.

A pH SCALE is the one that determine the acidity and basicity of a certain substance.