# Equation of the best fit line linear trendline for

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Equation of the best-fit line (linear trendline) for Light Absorbance vs. Calcium Concentration.Y = 0.0041x + 0.0058Concentration of calcium:.0856 = 0.0041x + 0.0058X = 19.46 ppmDouble concentration because of dilution: 38.92 ppm
Hawbaker 9Calcium Hardness:38.92ppm Ca2+ x ((100.09 g CaCO3/ (1 mol)) / (( 40.08 Ca2+)/ 1 mol)) = 97.19 ppm hardnessGraph 2: Light Absorbance vs. Magnesium ConcentrationCalculation 2: Magnesium concentration hardnessEquation of the best-fit line (linear trendline) for Light Absorbance vs MagnesiumConcentration.Y = 0.0079x + 0.0034Concentration of Magnesium:.0856 = 0.0079x + 0.0034X = 10.41 ppmDouble concentration because of dilution: 20.82Magnesium Hardness:20.82 ppm Mg2+ x ((100.09 g CaCO3) / (1 mol)) / ((24.31 g Mg2+/ 1 mol)) = 85.72 ppmhardnessCalculation 3: Total hardness of calcium and magnesiumTotal hardness value = calcium hardness + magnesium hardnessTotal hardness value:97.19 + 85.72 = 182.91 ppm
Hawbaker 10Table 2: Hardness calculated from AA analysisSampleCalculated hardnessfrom Calcium (ppm)Calculated hardnessfrom Magnesium(ppm)Total calculatedhardness (ppm)Water from Britafilter6595160Tap water @ ViewApt11595210Sink water @ EwingHall9684180Tap @ 365 EFairmount204122326Table 3: Calcium and magnesium percent errorCa and Mg concentration(ppm)Ca check standard* (ppm)Mg check standard* (ppm)% Error Ca% Error Mg1Ca: 1.03 ppmMg: 1.40 ppmCa: 3%Mg: 40%5Ca: 5.30 ppmMg: 5.03Ca: 6%Mg: .6%10Ca: 10.87 ppmMg: 9.90Ca: 8.7%Mg: 1%25Ca: 25.06Mg: 25.86Ca: .24%Mg: 3.4%Mg: 30Ca: 50Ca: 49.84Mg: 29.79Ca: .32%Mg: .7%Calculation 4: Percent error of calcium and magnesium% Error = ((check standard - concentration)/ concentration) x 100% Error = ((0.98 -1 ppm)/ 1 ppm) x 100% Error = 2%
Hawbaker 11Table 4: TDS observation after water evaporation occurredWater sampleObservationWater from brita filterStrong white residue, stronger than calciumTap water from View aptUndiluted sample had more white residuethan calciumSink water @ Ewing hallUndiluted had more white residue for ring,then diluted and last was calciumTap water @ 365 E FairmountUndiluted had more white residue for ring solowest TDS, then diluted, then calciumTable 5: EDTA serial titration to determine water hardnessWater sampleEDTA and # of dropsWater from brita filter1 drop sample6 drops of EDTA120 ppm hardnessTap water from View apt1 drop sample4 drops of EDTA80 ppm hardnessSink water @ Ewing hall1 drop sample9 drops of EDTA180 ppm hardnessDowntown house @ 365 E Fairmount1 drop sample11 drops of EDTA220 ppm hardness
Hawbaker 12Discussion:The hypothesis very closely resembled the findings from the actual results. The softestwater came from the water that was filtered from the Brita filter at 160 ppm and the secondsoftest water sample was my water sample from the on campus dorms at 180 ppm. The watersample from The View’s sink was very hard at a ppm of 210 and the hardest sample came from ahouse off campus at 326 ppm. These values from soft to hard were determined by table 2 of thecalculated combined hardness of magnesium and calcium from atomic absorbance numbers.During the experience of this experiment, I found the atomic absorption spectroscopyprovided the most distinguishable and justifiable differences in presenting water hardness. Theaccuracy of the AA spectroscopy was best supported by the percent error calculations. Thepercent error calculations were relatively low due to some exceptions. One appeared when the

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