indicators

• Litmus Paper: - filter paper that is treated with natural water soluble dye from lichens. Used to test the acidity or the basicity of a solution.
• blue litmus paper turns red under acidic conditions red litmus paper turns blue under basic or alkaline conditions
• Natural Indicators: - it contains flavin, a pigment molecule that changes colors according to the concentration of hydrogen ions in a solution. Some natural indicators extracted from red cabbage, onions, camote tops, red apple, and roses
• pH Meter - is a scientific instrument that measures the hydrogen-ion concentration (or pH) in a solution, indicating its acidity or alkalinity.
• Universal pH Indicator – a pH paper that can change into a whole range of colors and determine the pH value of a solution.
• Numeric scale - use to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions.