Determining the total hardness in water using complexometric titration with EDTA tutorial suitable for chemistry students. Complexation Titration: Determination of Total Hardness of Water The use of EDTA as a complexometric titrant for metal ions has been investigated in the past . You will use EDTA complexometric titration to determine the hardness of a responsible for hardness, and total water hardness is defined as the sum of the.

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Complexation Titration: Determination of Total Hardness of Water | Gabriel Lerona –

The standard CaCO3 is Depending on the water hardness we may use more concentrated or more diluted titrant. New York, ; p. Consequently, the results showed that the water in the Chemistry laboratory is very hard containing Use a small amount of water from a wash bottle filled with deionised water to wash the EDTA out of the funnel and into the flask.

Repeat the titration until you have ttotal results EDTA volumes that agree to with 0. Fundamentals of Analytical Chemistry by Douglas A. Data Analysis for Chemistry: Thus, for the end point, we should use the same indicator we use when titrating magnesium – that is Eriochrome Black T.

Determining Total Hardness in Water by Complexometric Titration

It was a job well done for her. The abovementioned reactions and techniques can also be done for different applications in connection to the comppexometric of EDTA and other complexing agents with metal ions.


The total concentration of dissolved calcium ions and magnesium ions in the water is 1. Using mL volumetric flask, Add 5 mL of ammonia based pH 10 buffer using a pipette 1.

Water hardness is a measure of the amount of calcium and determinatiion salts dissolved in water.

As it was explained above, calcium is complexed first, so to detect end point we can use indicator used for detection of end point of magnesium titration. Do you know this?

The ionised tirration of EDTA is shown on the right. Magnesium will be displaced by identical amount of calcium, and it will be titrated later, not changing final result. Keep swirling the conical flask during the titration to mix the contents. Stability constant of calcium complex is a little bit higher, so calcium reacts first, magnesium later.

Determination of total water hardness by complexometric titration

Balancer and stoichiometry calculator operating systems: Water hardness values are usually presented in terms of CaCO 3 because this is the most common cause of scaling or the precipitation of minerals which form limescale that can clog pipes, boilers and can decrease the life of toilet flushing pipes. In general this is a simple titration, with no other problems then those listed as general sources of titration errors.


Refill the burette if necessary, and repeat the titration. Moles of EDTA must be calculated using the results of the titration: Sample calculations are shown in Appendix. Water hardness can be measured using a titration with ethylenediaminetetraacetic acid EDTA.

Check that there are no air bubbles in the solution in the burette, and that there is no “air pocket” at the tip of the burette. Read mass of calcium carbonate in the titrated sample in the output frame. At the equivalence point of the titration: This could have been the reason why lathering of the soap is a little hard but rinsing it off is easy. These findings suggest that the water source in the laboratory is very hard. The formation of Ca-EDTA complex in the experiment helped the experimenters to elucidating the aspects of titration, such as the determination of its equivalence point, and indicator reactions in the identification of end point.

Further applications of EDTA and other complexometric titrations can be very useful in industrial and other health aspects.