Experiment 34.docx - Anjli Patel October 1 2019 Sarika...

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Anjli Patel October 1, 2019 Sarika Chauhan, Jade Waithe Experiment 34: An Equilibrium Constant Hypothesis As the concentration of NaSCN increases in each solution, the absorbance will then increase as well. Report Sheet (Data) Part A Molar Concentration of Fe(NO3)3 0.2 Molar Concentration of NaSCN 0.001 Part A blank 1 2 3 4 5 Volume of NaSCN (mL) 0 1 2 3 4 5 Moles of SCN- 0 0.000001 0.000002 0.000003 0.000004 0.000005 [SCN-] 0 0.0004 0.00008 0.00012 0.00016 0.0002 [FeNCS 2+] 0 0.0004 0.00008 0.00012 0.00016 0.0002 Absorbance 0 0.048 0.164 0.224 0.319 0.397 Part B Molar Concentration of Fe(NO3)3 0.002 Molar Concentration of NaSCN 0.002 Part B 6 7 8 9 10 Volume of Fe(NO3)3 (mL) 5 5 5 5 5 Moles Fe3+ ( initial) 0.00001 0.00001 0.00001 0.00001 0.00001 Volume NaSCN (mL) 1 2 3 4 5 Moles SCN- 0.000002 0.000004 0.000006 0.000008 0.00001 Absorbance 0.176 0.413 0.563 0.756 0.819
Anjli Patel October 1, 2019 Sarika Chauhan, Jade Waithe Part C: Calculations of Kc [FeNCS2-], equilibrium, from calibration curve (mol/L) 8.63E- 05 2.03E- 04 2.76E- 04 3.71E- 04 4.02E- 04 Moles FeNCS 2+ at equilibrium (10mL) (mol) 8.63E- 07 2.03E- 06 2.76E- 06 3.71E- 06 4.02E- 06 [Fe3+], equilibrium 6 7 8 9 10 Moles of Fe3+, reacted (mol) 8.63E- 07 2.03E- 06 2.76E- 06 3.71E- 06 4.02E- 06 Moles of Fe3+, equilibrium (mol) 8.63E- 07 2.03E- 06 2.76E- 06 3.71E- 06 4.02E- 06 [Fe3+], equilibrium (unreacted) (10mL) (mol/L) 8.63E- 07 2.03E- 06 2.76E- 06 3.71E- 06 4.02E- 06 [SCN-], equilibrium Moles of SCN-, reacted (mol) 6 7 8 9 10 Moles of SCN-, equilibrium (mol) 9.14E- 06 7.97E- 06 7.24E- 06 6.29E- 06 5.98E- 06 [SCN-], equilibrium (unreacted) (10 ml) (mol) 1.14E- 06 1.97E- 06 3.24E- 06 4.29E- 06 5.98E- 06 Kc=[FeNCS2+]/ [Fe3+][SCN] 1.14E- 04 1.97E- 04 3.24E- 04 4.29E- 04 5.98E- 04 Average Kc 4.19E+05 Standard Deviation of Kc 2.87E+05 Relative Standard Deviation of Kc 68.55%
Anjli Patel October 1, 2019 Sarika Chauhan, Jade Waithe Graphs 0 0 0 0 0 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 f(x) = 2038.57 x − 0.01 R² = 0.99 Absorbance vs. Concentration of FeNCS2+ Concentration of FeNCS2+ Absorbance Calculations A. Set of Standard Solutions to Establish a Standardization Curve 2. Moles of SCN- (mol) = Molar Concentration of NaSCN * Liters of NaSCN used .001 M NaSCN *.001 L NaSCN = 1.00* 10 -6 Moles of SCN- for Solution 1 3. [SCN-] (25 mL) (mol/L) = Moles of SCN- * .025 L SCN- 1.00* 10 -6 Moles of SCN- * .025L SCN- = 4.00* 10 -5 concentration of SCN- for Solution 1 4. [FeNCS 2+ ] (mol/L) = Moles of SCN- * .025 L [FeNCS 2+ ] 1.00* 10 -6 Moles of SCN- * .025L [FeNCS 2+ ] = 4.00* 10 -5 concentration of FeNCS 2+ for Solution 1 B. Absorbance for the Set of Test Solutions
Anjli Patel October 1, 2019 Sarika Chauhan, Jade Waithe 2. Moles of Fe 3+ , initial (mol) = Molar Concentration of Fe(NO 3 ) 3

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