To find the pH of the following samples by using pH paper / universal indicator.
pH is defined as the negative logarithm(base 10) of the hydrogen ion concentration in moles per litre. pH is written as:
Hydrogen ions cannot exist alone, but they exist after combining with water molecules. Thus, H+must always be shown as H+(aq) or hydronium ion(H3O+):
Neutral solution has pH value 7. pH of acid solution is always less than 7, whereas that of alkaline solution is always more than 7. pH of pure water is 7 or [H+]=10-7 mol/L .
pH indicator is a chemical that turns different colours in different media. For example, blue litmus turns red in acidic medium, the red litmus turns blue in alkaline medium.
Litmus solution is a purple dye, which is extracted from a Thallophyte known as Lichen. Litmus solution when in neutral medium (i.e., neither acidic nor basic) is greenish in colour.
Litmus solution and litmus paper are commonly used as an indicator. pH paper is a piece or a strip of paper which is coated with pH-indicator.
A scale for measuring hydrogen ion concentration is known as pH scale. In the term pH, p stands for 'potenz' in German meaning power.