1. Presented By: Jared Poist and Monique Gray

2. Hard Water Hard water is a detectable amount of dissolved cations in water. Drinking hard water poses no known health risk. It causes water to taste bad. One of the main problems with hard water is it leaves behind residues and precipitants on a majority of surfaces.

3. EDTA Ethylenediaminetetracetic Acid This chemical compound forms 1:1 metal complexes with the majority of the metal cations. EDTA plays a strong role as a metal-binding agent in industrial processes, products/supplies such as cleaning agents and food additives that prevent metal- catalyzed oxidation of food.

4. Biochemistry Application EDTA is used in biochemistry to stop enzymatic activity by binding with the divalent cations from the active site of enzymes, thus, preventing it from functioning. Common divalent cations are Ca2+ and Mg2+.

5. EDTA Continued EDTA is a mutlidentate ligand or a chelating ligand The chelate effect is the ability of multidentate ligands to form more stable metal complexes than those formed by similar monodentate ligands. The more electrons pairs an atom has available for binding the more stable the complex will be.

6. Compleximetric Titrations Basically, titrations that are based upon forming metal- cation complexes with different ligands.

7. EDTA Acid-Base Titration

8. Water sample Information Deer Park Spring Water Filtered Water (from Jareds home refrigerator ) Tap Water Data (came from previous lab experiment)

9. Introduction to Our Experiment Plan: use the EDTA titration technique to find the hardness of water for filtered water and spring water. Hypothesis: (1) The hardness in tap water should be higher than both filtered water and spring water. (2) The hardness in filtered water should be higher than spring water

10. Procedure: Standardizing EDTA Prepared Solutions: 0.1 CaCl 2 solution and 0.01 EDTA Solution Added 3mL of CaCl 2 into a 250mL flask, 5mL ammonia buffer (pH 10), and 5 drops of calmagite indicator Standardized EDTA and recorded 3 good trials

11. Standardizing EDTA Results Trial #EDTA Added (mL)Molarity of EDTA 115.20 mL0.01973 M 214.0 mL0.02140 M 315.0 mL0.02000 M Average Molarity: 0.0204 M

12. Procedure Continued (1) Calibrated a pH meter with standard solutions, and used the pH meter to make a buffer with pH 10. (2) Added 3mL ammonia buffer, 25mL water (sample), and 5 drops indicator. (3) Three good trials for each water sample.

13. Calculations mL CaCl2 added x 0.100 Ca2+ M / 1000 mL x 1mol EDTA/ 1 mol Ca2+ x 1 / L EDTA added = Molarity of EDTA L of EDTA x Average Molarity x 1 mol Ca2+/1 mol EDTA x 1/ 0.025L = concentration of hardness Ca2+ Molarity x grams Ca2+/ 1 mol x 1000mg/1g = ppm

14. EDTA Titration Results Trial #Spring WaterAmount EDTA Added mL 125mL1.20 mL 225mL1.20 mL 325mL1.10 mL Trial #Filtered waterAmount EDTA Added mL 125 mL1.9 mL 225 mL1.7 mL 325mL2.01 mL

15. EDTA Titration Results Trial # 1Amount Tap Water mLAmount EDTA Added mL 125 mL2.68 mL 225 mL2.31 mL 325 mL2.25 mL

16. Hardness of Water Samples Results Spring Water Trial #Ca2+ Molarityppm 10.000979239.244 20.000979239.244 30.000897635.974 Filtered Water Trial #Ca2+ Molarityppm 10.001550462.1370 20.0013872055.5970 30.0016401665.7343

17. Hardness of Water Sample Results Tap Water TrialCa2+ Molarityppm 10.0023694.584 20.0020381.358 30.0019879.354

18. Conclusion We found that our first hypothesis was correct, which stated that tap water had a greater hardness than spring and filtered water. We found that our second hypothesis was true, which stated that filtered water would have a higher hardness than spring water.