The hardness of water was determined using the methods of titration, conductivity, and pH analysis. The mean and uncertainty of CaCO3 is 134±36.0 ppm. An error that could have potentially happened could be that the equivalence point was not correctly established causing inaccurate data.
BACKGROUND: 1In hard water there is a high amount of mineral content present in the water.
Most of the mineral content that is present in water are Ca2+ and Mg2+ ions. Even though hard water does affect a person’s health, hard water can still have harmful effects in an industrial environment, appliances in a household setting, and certain cleaning task. 2For example, when hard water repeatedly goes through pipes, the water causes deposits that eventually build up and clog the pipes. When cleaning dishes the presence of hard water can be detected when a layer of film is present on the dishes.
Soap becomes less effective when hard water is present because the soap will bond with the minerals in the water. PROCEDURE: Hirko, R. Chemistry 112L General Chemistry I Laboratory, Seventh Edition; bluedoor: Minnetonka, MN, 2013 RESULTS:
Table 1. Ca2+/Mg2+ in tap water via EDTA titration. Table 1 results were determined by pH analysis and EDTA titration. The moles of EDTA was found by using the EDTA concentration of 0.025 mol/L. Table 2. Conductivity probe calibration Figure 1. Conductivity of standard NaCl using conductivity probes.
1″H2OKits.com Water Blog.” Negative Effects of Hard Water. H20 Kits, 16 Sept. 2008. Web. 11 Oct. 2013. 2”Water Hardness.” Water Hardness. Freshwatersystems, n.d. Web. 12 Oct. 2013. DISCUSSION: The mean and uncertainty for CaCO3 for tap water was determined to be 134±36.0 ppm. For the EDTA titration trial 2 and trial 3 had the same results of 125 ppm compared to trial 1, which had a higher ppm of 150. The readings for the
hardness of water for the 3 different trials are not similar and differ in values. The CaCO3 value for the volumetric data was 134 ppm, the value for NaCl was 180 ppm, and the value for 442 was 248 ppm.
The hardness of water can never be definitive because the water in Brookings may be different than the water in Sioux Falls. If it was possible to always have the same amount of mineral concentration then it would be definitive. Errors that could that potentially happened is when titrating it was difficult to tell when the equivalence point actually occurred, causing more or less amount of EDTA to present. Not knowing the when the equivalence point actually occurred would cause inaccurate values because the volume would be incorrect. Another error could be that the magnetic stirrer was spinning fast enough to mix the solution properly.
This would cause excess EDTA to be present causing inaccurate results. An improvement for this lab would be test different hard water sources rather than just one faucet.