How can you tell an acid from base?

Answer (new):

There are many ways to test a solution. Some of the most popular are:

- Litmus paper is paper treated with litmus powder. It turns red in pH<4.5 (acidic) and blue in pH>8.3 (basic.)

- Pheophthalein is a colourless liquid that turns pink in basic solution. The more concentrated the base, the deeper the pink.

- Universal indicator is a solution that is added to a solution. At pH<3 it is red and it goes through the colour spectrum until it hits violet when in a solution of pH>11

- Hydrion papers are papers treated with a universal indicator that are marketed commercially.

•An acid is a proton donor

•A base is a proton receiver

HCl + OH- >> Cl- + HOH

•A Lewis acid receives a pair of electrons

•A Lewis base donates a pair of electrons