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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A few drops of 1: The total concentration of dissolved calcium ions and magnesium ions in the water is 1.

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. Online Journal Hepler, P. New York, ; p. After that, the CaCl 2 solution was titrated with the EDTA solution until the color changed from wine red to pure blue.

However, in this experiment, an average of Hardneas a standard solution of EDTA. 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.

Depending on the water hardness we may use more concentrated or determibation diluted titrant. In this experiment, the tap water that was used is suspected to be hard. Calcium carbonate concentration expressed in parts per million are usually the criteria for the determination if a particular water sample is hard.

Hard Water Calcium and Magnesium. Chemistry of Hard Water and Soft Water. That means Eriochrome Black T.


The average total hardness of the sample is Calcium stearate and magnesium stearate or soap scums makes it hard to lather but can be rinsed off easily Helmenstine, dteermination According to an online article from U. Skip to main content.

Determination of water total hardness by complexometric titration

Can you apply this? Experimenters are now able to learn the basics and techniques in this kind of titration. Moles of EDTA must be calculated using the results of the titration: Use the rough titration above as a guide as to where the endpoint is. Thus, for the end point, we should use the same indicator we use when titrating magnesium – that is Eriochrome Black T.

Magnesium will be displaced by identical amount of calcium, and it will be titrated later, not changing final result. For the standardization, The standard CaCO3 is Add 5 mL of ammonia based pH 10 buffer using a pipette 1. EDTA dissolved in water forms a colourless solution.

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. Conversely, it does not affect much of the whole process since the indicated linearity of the results is precise, though the accuracy is not described.

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

Water hardness is measured in parts per million or milligrams per liter. Small excess of ammonia doesn’t hurt, as we finally add ammonia buffer and change of pH by several tenths is not a problem.

Such explanations could have been also the possible reasons why liquid detergents synthetic soap are used in washing the glassware rather than the soap or bar detergents. Hard water should be not used for washing it reduces effectiveness of detergents nor in water heaters and kitchen appliances like coffee makers that can be destroyed by scale.


To perform titration we will need titrant – 0. The most deternination problem is spotting the end point, which is not always sharp. Use this volume of EDTA as a guide in repeating the titration. Water Hardness and Alkalinity. Read mass of calcium carbonate in the titrated sample in the output frame.

Click here to sign up. This could have been the reason why lathering of complexomstric soap is a little hard but rinsing it off is easy. Consecutively, after reading the coomplexometric volume of gy titrant in the buret, the sample was titrated with the EDTA solution until the color changed from wine red to pure blue.

Fill the volumetric flask to the mark with deionised water. Consequently, the results showed that the water in the Chemistry laboratory is very hard containing Slowly add the EDTA 1 mL at a time until you start to see indications of a colour change in the solution, that is, a spot of blue appears before disappearing. Two more replicates were done to obtain the average hardness of water.

Note the approximate endpoint of the titration.

Determining Total Hardness in Water by Complexometric Titration

In this light, the water in the laboratory is suggested to be treated and should be softened in order to avoid several plumbing problems watre to the production of scums if it will still be used. Complexometric titration is one of the best ways of measuring total water hardness.

Using mL volumetric flask, This error is equivalent to 0.

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