Amazing Chemistry Experiments

A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over wider pH range values as the hydrogen ion concentration changes depending on the environment. The indicator itself can also be impregnated onto paper to form indicator strips. • A very strong acid (≤ 3) is red. A weak acid (4-6) is orange to yellow. A neutral solution (7) is green. A weak base (8-10) is blue. A strong base (≥ 11) is indigo/violet. • The colour range is