Prestige Institute of Management & Research Sessional Paper PDF

## Prestige Institute of Management & Research - BHOPAL ### PROBLEM-1 - A sample of water is found to contain the following dissolved salts in milligrams per liter: - Ca(HCO₃)₂ = 89 - MgSO₄ = 40 - MgCl₂ = 95 - Calculate temporary and permanent hardness and total hardness. | Name of h...

## Prestige Institute of Management & Research - BHOPAL ### PROBLEM-1 - A sample of water is found to contain the following dissolved salts in milligrams per liter: - Ca(HCO₃)₂ = 89 - MgSO₄ = 40 - MgCl₂ = 95 - Calculate temporary and permanent hardness and total hardness. | Name of hardness causing salt | Amount | Molecular Weight | Amount equivalent to CaCO₃ (mg/l) | |---|---|---|---| | Mg(HCO₃)₂ | 73 | 146 | 50 | | Ca(HCO₃)₂ | 111 | 162 | 50 | | MgSO₄ | 40 | 120 | 33.3 | | MgCl₂ | 95 | 95 | 100 | - Molecular Weight: - Mg(HCO₃)₂ = 24 + 2(1 + 12 + 3(16)) = 146 - Ca(HCO₃)₂ = 40 + 2(1 + 12 + 3(16)) = 162 - MgSO₄ = 24 + 32 + 4(16) = 120 - MgCl₂ = 24 + 2(35.5) = 95 - Temporary hardness = Mg(HCO₃)₂ + Ca(HCO₃)₂ = 50 + 50 = 100 mg/l - Permanent hardness = CaCl₂ + MgSO₄ + MgCl₂ = 100 + 33.3 + 100 = 233.3 mg/l - Total hardness = Temporary hardness + Permanent hardness = 100 + 233.3 = 333.3 mg/l ### PROBLEM-2 - 0.28 grams of CaCO₃ were dissolved in HCl and the solution was made upto 1 Litre with distilled water. - 100 ml of the above solution required 28 ml of EDTA solution on titration. - 100 ml of this hard water sample consumed 33 ml of the same EDTA solution using EBT indicator. - 100 ml of this water after boiling and filtering required 10 ml of EDTA solution in titration. - Calculate the permanent and temporary hardness of water sample in ppm. - **Given:** - Standard hard water = 0.28 gram/liter of CaCO₃ - **Therefore 1 ml of standard hard water will be 0.28 mg of CaCO₃.** By Standardization of EDTA: - 100 ml of SHW = 28 ml of EDTA - 28 mg of CaCO₃ = 28 ml of EDTA - 1 mg of CaCO₃ = 1 ml of EDTA - **For total hardness:** - 100 ml of sample water requires 33 ml of EDTA - 100 ml of sample water = 33 ml of CaCO₃ 1000 ml of sample water = (1000 x 33) / 100 = 330 mg/liter - **Total Hardness = 330 mg/l** - **Calculation for permanent hardness:** - 100 ml of boiled & filtered water = 10 ml of EDTA - 100 ml of boiled & filtered water = 10 mg of CaCO₃ - 1000 ml of boiled & filtered water = 1000 x 10 / 100 = 100 mg/l - **Permanent hardness = 100 mg/l** - **Temporary hardness = Total hardness - Permanent hardness = 330 - 100 = 230 mg/liter** - **Answer:** - Permanent hardness in water = 100 ppm - Temporary hardness in water = 230 ppm