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Experiment 10: The Chemistry ofNatural WatersJohn Smith 4/12/18Chem 113Section 004Group Members: Sarah Cohen (desk 39)and Jake Joe(desk 38)TA: Dennis Winston
Introduction:While studying the different component of water, a very common piece of information that is looked at is the hardness of water. This is an important component to look at because it is able to tell a person about the mineral content of the water that the individual is studying. The elements that causes water to be looked at as hard is the presence of calcium and magnesium (4Thompson). If water is looked at as having 60mg/L or less of magnesium and calcium it is known as being soft (6Harwich). It is important to know the hardness of water in different areas because this allows an individual to know what ions are present in the water one may use for drinking, cooking or even cleaning. By understanding the different hardness of water in various places it allows for a person to better understand how materials such as detergent will react with the water being used. There is something known as the AA or Atomic Absorption method and theethylenediaminetetracetic acid (EDTA). These two methods both allow for water hardness to be tested in different ways. The AA method excites magnesium and calcium through the use of light. This is done in order to produce monochromatic light. After this light is produced, it will travel to a flame and when it hits the liquid of the flame aerosol is produced. Once the aerosol is produced magnesium and calcium will absorb the light that has been created. The light created by the magnesium and calcium will then travel through a narrow slit that opens up to a space with metal atoms. The metal atoms will absorb the light that is passing through the slit. Once thisis completed the concentration of the metal in the water sample provided is determined (4Thompson). The EDTA is found through the process of titration. A drop of the EDTA is mixed in with water sample and this is then carried out through the use of a titration. The EDTA will dissolve into the water and create a colorless solution. The solution will be colorless because the
EDTA is a weak acid that is reacting with water. A change in color will be observed and this will occur when EDTA completely mixes with all the present cations (4Thompson). The focus of the study was to look at how much calcium and magnesium was present within the water samples that were present. The samples presented were from State College, PA, Potomac, MD and Bucks County, PA. The water that is readily available in the State College areawill most likely be hard because it comes from well sources which contain a large amount of calcium due to the fact that the water is coming from the ground (2Bucks). The water from Maryland will be fairly comparable to the water being looked at in Pennsylvania due to the fact that both of these areas are in the same region. The water from the Maryland sample will also be