Experiment 8
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Separation of Cations By Andrew Feigley Purpose: The purpose of this lab is to conduct selective analytical techniques including masking and ion exchange. To determine the concentration of Zn, Mg, Na, and H+ in an unknown solution. Purpose: Four different determinations were conducted. The first two were titration use NaOH. The initial titration gave the total concentration of all ions. The second titiration was preformed after passing the unknown through a cation exchange resin to give the concentration of H+. The last two titrations were done by using EDTA in order to determine metal ion concentrations of Mg and Zn. The final titration was done using a masking agent of KCN to give the concentration of Mg. Data: Part 1 KHP(g) NaOH(ml) Molarity trial 1 0.5114 28.1 0.0891 trial 2 0.5102 28.1 0.0889 trial 3 0.5112 28.4 0.0881 Molarity of NaOH: 0.0887 Trial Volume of Unknown (mL) Volume of NaOH (mL) Mole of NaOH pH (mL) 1 25.0 1.0 8.87 × 10-5 3.0 2 25.0 1.0 8.87 × 10-5 2.6 3 25.0 1.0 8.87 × 10-5 2.5 [H+] = .0046 Part 2 trial unknown (mL) H2O (mL) NaOH (mL) a 1.0 20.0 6.10 b 1.0 20.0 5.40 c 1.0 20.0 5.50 [ions] = 0.502 Part 3 Standardization of EDTA with CaCO3 mL EDTA CaCO3 ammonia buffer trial 1 1.5 mL .1M 3 mL 5 mL trial 2 1.5 mL .1 M 3 mL 5 mL trial 3 1.5 mL .1 M 3 mL 5 mL Data Missing for Mg and Zn determination Part 4 KCN (g) EDTA (mL) Starting pH Sample #1 1.0002 6.7 10.62 Sample #2 0.9991 6.6 10.62 Sample #3 0.9997 6.6 10.57 Calculation: Part 1 ππππ’ππ ππππ» × πππππππ‘π¦ ππππ» + (10−ππ» × ππππππ€π ππππ’ππ) = πΆππππππ‘πππ‘πππ π» + πππ‘ππ ππππ’ππ Part 2 Average Volume NaOH × Molarity NaOH × πππ π» + × ππππ’ππ ππ ππππππ€π πππ ππππ» = πΆππππππ‘πππ‘πππ ππ ππππ Part 3 π΄π£πππππ ππππ’ππ πΈπ·ππ΄ × πππππππ‘π¦ πΈπ·ππ΄ × πππ ππ πππ ππ × πππ πΈπ·ππ΄ π΄π£πππππ ππππ’ππ ππππππ€π = πΆπππππππ‘πππ‘πππ ππ πππ ππ Part 4 π΄π£πππππ ππππ’ππ πΈπ·ππ΄ × πππππππ‘π¦ πΈπ·ππ΄ × πππ ππ × πππ πΈπ·ππ΄ π΄π£πππππ ππππ’ππ ππππππ€π = πΆπππππππ‘πππ‘πππ ππ Standardization of NaOH π΄π£πππππ πππ π ππ πΎπ»π × πππππ πππ π πΎπ»π = πππππππ‘π¦ ππππ» × πππ ππππ» × πππ πΎπ»π π΄π£πππππ ππππ’ππ ππππ» Standardization of EDTA πππ π ππ πΆππΆπ3 × πππππ πππ π πΆππΆπ3 = πππππππ‘π¦ πΈπ·ππ΄ × πππ πΈπ·ππ΄ × πππ πΆππΆπ3 π΄π£πππππ ππππ’ππ πΈπ·ππ΄ Conclusion: This Lab did not work very well. Part three data was never completed and there were groups that didn’t follow the agreed upon procedures.
