Total Hardness Determination with EDTA Method

The aim of the experiment is the determination of Total Hardness of supplied hard water sample by EDTA method.

The principle is that the Disodium salt of EDTA reacts with hard water and consumes all the hardness producing cations in alkaline medium, and the excess of this reagent is indicated by the reaction of the indicator Eriochrome Black-T (EBT).

The apparatus required are: i. Burette (50ml), ii. Burette Stand, iii. Beaker (500ml), iv. Conical flask (250ml), v. Pipette (2ml), vi. Measuring Cylinder (100ml), vii. Wash bottle.

The chemicals required are: i. EDTA solution, ii. Eriochrome Black-T Indicator (EBT), iii. Basic Buffer solution (NH OH + NH Cl)

Hardness is the property of water which prevents the lathering of soap and increases the boiling point of water. It has two types: a) Temporary Hardness (due to bicarbonates of Ca and Mg), and b) Permanent Hardness (due to Cl , SO , NO of Ca and Mg)

The Eriochrome Black-T (EBT) indicator is used to indicate the end point of titration by changing the color of the solution from wine-red to clear blue when the excess of EDTA reagent has reacted with the hard water.

The principle of complexometric titration involves the reaction of the disodium salt of EDTA with hard water in an alkaline medium to consume the hardness-producing cations and then using an indicator to determine the end point of titration.

The aim of the experiment is to determine the total hardness of the supplied hard water sample using the EDTA method.

The hardness of water is generally expressed as equivalent parts of CaCO3 in specific parts of water, such as in million parts of water or in liter of water.

Hardness is the property of water which prevents the lathering of soap and increases the boiling point of water. It is classified into two types: temporary hardness (due to bicarbonates of Ca and Mg) and permanent hardness (due to Cl-, SO4^2-, and NO3- of Ca and Mg).