Introduction
Acidity of water or wastewater is its quantitative capacity to react with a strong base to a designated pH. Strong mineral acids, weak acids such as carbonic and acetic, and hydrolyzing salts such as iron or aluminium sulphates may contribute to the measured acidity according to the method of determination.
Acids contribute to corrosiveness and influence chemical reaction rates, chemical separation and biological processes.
Principle
Hydrogen ions present in the sample as a result of dissociation or hydrolysis of solutes react with additions of standard alkali. Acidity thus depends on end point pH or indicator used.
Apparatus
1. pH meter
2. Magnetic stirrer
3. Pipets, volumetric
4. Flasks, volumetric, 1000, 200, 100 ml
5. Burets
Procedure
1. Take 100 ml sample in 250 ml beaker
2. Note initial pH of the sample
3. Slowly stir and add 0.1 N NaOH solution with the help of burette to
achieve pH of 8.3.
4. Note the total volume of NaOH added.
Calculation
Total Acidity CaCO3 = ml of NaOH x N of NaOH x 50000 / ml of Sample taken