How to determine hardness of water by EDTA method? (Procedure and problems on hardness) скачать в хорошем качестве

How to determine hardness of water by EDTA method? (Procedure and problems on hardness)

Estimation of hardness of water by EDTA method. Calculation of total, permanent and temporary hardness. Problem-solving. Types of hardness is discussed. Some problems are worked out in detail. You will be able to explain the principle of estimation of hardness by EDTA method. You will be able to describe the procedure of this method. You will be able to perform the experiment. You will be able to calculate the total, permanent and temporary hardness of the given water sample. Estimation of Hardness (by EDTA method) -Procedure Preparation of solutions Standard hard water – I g (1000 mg) of CaCO3 dissolved in dil. HCl and made up to 1L (1000ml) 1ml of std. hard water contains 1mg of CaCO3 Ammonia buffer – 67.5 g of NH4Cl in 570 ml conc. ammonia solution –diluted to 1L Indicator [Eriochrome black-T] (EBT) - Blue colour dye - 0.5 g EBT in 100ml alcohol Standardization of EDTA Burette solution – EDTA solution Conical flask – 20 ml of std. hard water + 10ml ammonia buffer + 2 drops of EBT End point – wine red to steel blue Estimation of total hardness of the given water sample Same as above – replace std. hard water with the given water sample Volume of EDTA consumed at the end point –V1 ml Volume of EDTA consumed at the end point –V2 ml Estimation of permanent hardness of the given water sample Same procedure as in step I – replace std. hard water with the boiled water sample Volume of EDTA consumed at the end point –V3 ml Principle of Hardness (by EDTA method) The hardness producing ions (Ca2+ and Mg2+) present in the water combines with Eriochrome black-T (EBT) to form an unstable complex (wine red) When titrated with EDTA (Ethylene diamine tetra acetic acid), the Ca2+ and Mg2+moves from EBT to EDTA to form a stable complex at pH 9-10 leaving the free EBT(steel blue) Calculation of Hardness Standardization of EDTA 20 ml of std. hard water consumed V1 ml of EDTA Estimation of total hardness 20 ml of hard water sample consumed V2 ml of EDTA Estimation of permanent hardness 20 ml of boiled water sample consumed V3 ml of EDTA Special case: If 0.01M EDTA is used I Estimation of total hardness 20 ml of hard water sample consumed V1 ml of EDTA 20 ml of hard water sample contains V1 mg of CaCO3 Calculation of Hardness Estimation of permanent hardness 20 ml of boiled water sample consumed V2 ml of EDTA 20 ml of boiled water sample contains V2 mg of CaCO3 III Estimation of temporary hardness IV Estimation of temporary hardness Example 1. Standard hard water was prepared by dissolving 0.2g of CaCO3 in dil. HCl and then diluted to 1L with distilled water. 50 ml of std. hard water consumed 25 ml of EDTA. 50 ml of hard water consumed 20 ml of EDTA. 50ml of boiled water sample consumed 15 ml of the same EDTA solution. Calculate the total, permanent and temporary hardness. Solution -1000 ml of std. water contains 200 mg of CaCO3 50 ml of std. hard water sample contains 10 mg of CaCO3 50 ml of std. hard water consumed 25 ml of EDTA 50 ml of hard water consumed 25 ml of 0.01M EDTA. 50ml of boiled water sample consumed 18 ml of the same EDTA solution. Calculate the total, permanent and temporary hardness. Estimation of permanent hardness III Estimation of temporary hardness Standard hard water was prepared by dissolving 1.5 g of CaCO3 in dil. HCl and then diluted to 1L with distilled water. 50 ml of std. hard water consumed 23 ml of EDTA. 50 ml of hard water consumed 19 ml of EDTA. 50ml of boiled water sample consumed 10 ml of the same EDTA solution. Calculate the total, permanent and temporary hardness. 2. 100 ml of hard water consumed 32 ml of 0.01M EDTA. 100ml of boiled water sample consumed 21 ml of the same EDTA solution. Calculate the total, carbonate and non-carbonate hardness. 50 ml of boiled water sample consumed 18 ml of EDTA 50 ml of boiled water sample contains 18 mg of CaCO3