0732 ppm caco 3 28 ppm caco 3 table 7 overall

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+ 0.732 ppm CaCO 3 = 2.8 ppm CaCO 3 Table 7. Overall Hardness Values of samples in CaCO 3 for AA Sample Hardness Value in CaCO 3 (ppm) Berks County Tap 5 -1.575 Nittany Apartments Tap 6 75 Fairmount Ave Tap 7 188 Poland Spring Bottled 8 2.8 Table 8 and Table 10 demonstrate results for EDTA unsoftened and softened samples. Softened samples were treated with resin. Number of drops is an average value from two trials. M EDTA ×V EDTA = M ion ×V ion 10
( M EDTA ×V EDTA ) ( V ion ) = M ion ( 2.00 × 10 4 ) ( 4.00 × 10 6 ) ( 1 ) = 8.00 × 10 10 moleCaCO 3 1 L × 100 gCaC O 3 1 mole × 1000 mgCa C O 3 1 gram = 8 × 10 5 mg CaC O 3 1 L ( h Note: if sample has a dilution factor of 1:1, molarity has to be multiplied by two. Table 8 . Results of EDTA Titration (Unsoftened Samples) Sample # Drops to Achieve Equivalence (Average) Molarity CaCO 3 (moles/L) Concentration CaCO 3 (ppm) Berks County Tap 5 9 0.0018 180 Nittany Apartments Tap 6 4 0.0016 160 Fairmount Ave Tap 7 6 0.0024 240 Poland Spring Bottled 8 4 X 10 6 8 X 10 -10 8 X 10 -5 Percent error (%) is calculated below in Table 9 and can be calculated using the equation below. Values are taken from AA Standards ( Table 3 and Table 4.) | Theoretical ( 1.000 ) Actual ( 0.94 ) Theoretical ( 1.000 ) | × 100 = 6.0 Lastly, percent change (%) is calculated to compare results from EDTA titration using original samples to EDTA titration with soften samples shown in Table 10. Change = ( ppmCaC O 3 of original water sample ) −( ppmCaC O 3 of softened water sample ) ppm CaCO 3 of original water sample × 100 Percent change for “Poland Spring Bottled” sample was non applicable, sample calculation listed above. Table 9. Percent Error for Ca 2+ and Mg 2+ using AA Standard Theoretica l Ca Actual (Check Standard) Percent Error Theoretica l Mg Actual (Check Standard) Percent Error 11
1.000 0.94 6.0 % 1.000 1.06 6.0 % 5.00 4.84 3.2 % 5.00 4.90 2.0 % 10.00 9.88 1.2 % 10.00 10.03 0.3 % 25.0 25.74 3.0 % 25.0 25.75 3.0 % 50.0 51.99 4.0 % 30.0 29.61 1.3 % Table 10. Results of EDTA Titration (Resin Softened Samples) Sample # Drops to Achieve Equivalence (Average) Concentration CaCO 3 (ppm) Percent Change (%) Berks County Tap 5 1 20 88 Nittany Apartments Tap 6 2 80 50 Fairmount Ave Tap 7 4 160 33 Poland Spring Bottled 8 - - - IV. Discussion The hypothesis for the following experiment was that the “Berks County Tap” sample would be the hardest. “Nittany Apartment Tap” and “Fairmount Ave Tap” samples would be moderately hard, and “Poland Spring Bottled” sample would be the softest in water hardness. The results for the AA test did not support the hypothesis. The “Fairmount Ave Tap” sample came out to be the hardest, following “Nittany Apartment Tap” sample, “Poland Spring Bottled” sample and softest “Berks County Tap” sample. The “Berks County Tap” sample is an outlier in the data found. Upon finding percent error for the AA machine, none of the values are significant enough in error to confirm outlier due to machine issues. The “Berks County Tap” sample could have been too soft for calculation using the best-fit line. Although 12
according to the article Reading Eagle , Berks County has issues with hard water throughout the area.

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