Hardness of Water

845 Words4 Pages
Hardness of Water Controlled Assessment Part 1 A sample of water can be ‘hard’ if calcium or magnesium ions have been dissolved in the sample of water. If soap is added to hard water, it will react with the ions to form a solid scum, and once the soap has reacted with all of the ions, the rest of the soap works for washing. Some samples can be harder than others as there is more than one type of hardness of water, these are: Temporary hardness, when hardness is destroyed when the water is boiled, however boiling water is only an effective method of softening small volumes of water. It is time consuming and expensive for large quantities. (6) Permanent hardness, if boiling water has no effect on the hardness. (1) Each type of water has their advantages and disadvantages, but the damage that can be caused to water pipes and appliances from hard water means that water may need to be softened, through different methods. Permanent hard water contains dissolved sulfate ions, SO42– which do not decompose when heated up. They remain dissolved and do not react with calcium and magnesium ions – therefore the water stays hard even when boiled. (2). Permanent hardness is formed when calcium sulfate dissolves rocks. Rainwater can contain dissolved carbon dioxide, making it slightly acidic. There are two methods for softening hard water, this is either adding sodium carbonate to the water, or using ion exchange columns. The first way to measure the hardness in water is to perform titration, which is figuring out the concentration of a substance by the process of slowly adding a reagent until the substance fully reacts, in this case the reagent is soap solution (sodium carbonate) and the substance is hard water. A volume of water is put into a conical flask. Soap solution is added to it from a burette or pipette. The mixture is whirled to assist it to form lather/soap.

More about Hardness of Water

Open Document