Velez 2Introduction Water hardness by definition is the amount of calcium and magnesium that is dissolved inthe water. Water samples with high amounts of these minerals are considered hard, while sampleswith low amounts are considered soft. Hard water is a common occurrence, most commonly through deposits left on drinking glasses or on the faucet of tubs. This can be detrimental, however, because the minerals in the water could build up in pipes and other water-dependent appliances1. Some soaps and detergents can react with hard water and leave behind residue, called soap scum, which can be hard to remove. Because of this, many household cleaners are specially formulated to be able to cut through hard water stains and scum. On the other hand, drinking this water can contribute to the mineral intake required by humans, especially those who are calcium and magnesium deficient. The concentration of calcium and magnesium in water is typically measured by parts per million (ppm) of CaCO3. The four methods used in this experiment to determine hardness are AAanalysis, TDS, EDTA titration, and cation exchange2. Atomic absorption analysis is a technique used to determine metals that are dissolved or suspended in a solution. For this, an atomic absorption spectrophotometer must be used, so it will be the only section that is not done personally. The total dissolved solids, or TDS of the samples will be determined by dissolving a small amount of the sample and observing them. Next, cation exchange works by removing the divalent cations out of the water using a special resin. Finally, EDTA titration works by titrating the samples with various other solutions and observing the reaction that takes place via color change.
Velez 3For this experiment, we will be looking at the differences in hardness of water samples commercially and from home. One sample will be taken from 825 Bellaire Ave. In state college (sample 1)6, one will be taken from a Brita filter (sample 2)7, one will be taken from Fiji bottled water (sample 3)8, and one will be taken from Life bottled water (sample 4)9. None of the samples were diluted at any point in the experiment. It is predicted that the tap water sample will be the hardest or most contaminated, because from previous experience it is known that State College has harder water than usual, although Pennsylvania’s water is considered moderately soft3. Second in hardness will be the bottled water. According to a study from 2001 that looked atthe mineral levels of commercially bottled waters vs tap waters, the bottled waters were found to be significantly lower in mineral levels4. Last will come the Brita filtered sample. It is predicted that this sample will be the lowest in terms of hardness. According to Brita’s website, the filter cartridges used are designed to reduce the water’s temporary hardness5. Assuming that this is