The alkalinity refers to the measure of the capacity of the water to neutralize the acids. It can measure the bicarbonate, carbon dioxide, hydroxide ions, and carbonate naturally present in the water. The pH level of drinking water refers to how basic or acidic it is. The pH level refers to the hydrogen ions found in the water. How to Determine the Alkalinity of Water? Water sample is titrated against standard hydrochloric acid or sulphuric acid solution using phenolphthalein & methyl orange indicator. What Should be the Alkalinity in Drinking Water? Typically alkalinity of drinking water should be around 20-250 mg/L as CaCO3. # Alkalinity Daniel Arthur Alkalinity, or "acid neutralizing capacity," is measured by adding acid to the sample and figuring out the equivalent alkalinity in the water. The actual units for the alkalinity titration are moles or equivalents per volume (moles/L or eq/L). Converting alkalinity from eq/L to "mg/L as CaCO 3 " takes into account that one mole of 21. For efficient coagulation the water must be alkaline. Why? 22. Why do we use CO2 free distilled water for analysis? 23. Discuss the source and nature of acidity. 24. Discuss the significance of carbon dioxide and mineral acidity. 25. Can the pH of a water sample be calculated from a knowledge of its acidity? Why? 26. The various alkalinities are estimated by titrating the water sample against a standard acid using phenolphthalein and methyl orange indicators successively. Hydroxide ions is completely neutralized to water using phenolphthalein 2. DETERMINATION OF ALKALINITY OF WATER SAMPLE 1. Why is water alkaline? It is due to the presence of hydroxide, carbonate and bicarbonate ions. 2. What is the colour of phenolphthalein in acid and alkaline medium? Colourless in acid and pink in alkaline. 3. What are the ions determined by phenolphthalein? Hydroxide ion and half of carbonate D.O. present in the sample rapidly oxidises in equivalent amount of the dispersed divalent manganous hydroxide precipitate to hydroxides of higher valency states. In the presence of iodide ions and upon acidification, the oxidised manganese reverts to the divalent state, with the liberation of iodine equivalent to the original D.O. content in From the experiment, we calculated the change in total alkalinity (ΔT) (µmol/l). Further, the formula for calculating the mass of Calcium carbonate dissolved by erosion is. M (CaCO3) = 0.5 (mol Credit: Steve Gerner, USGS. Alkalinity is not a chemical in water, but, rather, it is a property of water that is dependent on the presence of certain chemicals in the water, such as bicarbonates, carbonates, and hydroxides. A definition of alkalinity would then be "the buffering capacity of a water body; a measure of the ability of the water Procedure for determination of acidity of water. Pipettes V mL (say 50 ml) of the sample to the flask. Added 1 or 2 drops of methyl orange indicator. The sample is then titrated against 0.02N standard NaOH. The endpoint is noted as colour changed from orange-red to yellow. The titrate value is recorded as V1. To determine the turbidity of the given water sample as per IS: 3025 (Part 10) - Reaffirmed 2002. 5.2 INTRODUCTION Turbidity is the technical term referring to the cloudiness of a solution and it is a qualitative characteristic which is imparted b