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Analysis for Iron(III) in KwFe (C204),(H20), Date 1. Lab Section Name A solution absorbs light in the visible region of the electromagnetic spectrum and shows a transmittance of 63%. What is the corresponding absorbance value for the solution? 2. A solution having a molar absorptivity of 20.83 L/mol cm in a 1-cm cell has a transmittance of 48.7%. What is the molar concentration of the absorbing species in the sample? 3. The following data were recorded using a spectrophotometer for a set of standard solutions containing cobalt(II)ions: Molar Concentration of Absorbance Cobalt(II)ions 0.22 1.62 x 10 0.35 1.98 x 10 0.58 2.62 x 10 0.77 3.14 x 10° (a) Construct a Beer's law graph for the standard solutions of absorbance versus molar concentration of the cobalt(II)ions. You may use graph paper directly from your laboratory notebook. (b) A test solution containing an unknown concentration of cobalt(II) ion was determined to have a transmittance of 35.2%. Using the Beer's law graph for the set of standard solutions, determine the molar concentration of the cobalt(II)ion in the test solution
Suppose it was determined in Experiment 398 that 0.610 mol of oxalate ion was present in 100 g of the coordination compound. How many milliliters of 0.500 M CaClz would be needed to precipitate the oxalate ion in a 0.100 g sample of the coordination compound? Assume the reaction: Ca?"(aq) + C2022 (aq) → CaC_04(s) 5. What is the purpose of using ascorbic acid in this experiment? Equations (See experiment 34 for details on the spectrophotometer and related equations. You will be performing Exp 34 this semester): Beer's Low A=abc A = absorbance a = molar absorptivity b = thickness of absorbing sample c=molar concentration of absorbing species Absorbance (A) vs %Transmittance: %T = 10 x 100% %T = % of light that passes through the sample. -log(%T/100%) - A
3. The following data were recorded using a spectrophotometer for a set of standard solutions containing cobalt(II)ions: Molar Concentration of Absorbance Cobalt(II)ions 0.22 1.62 x 10 0.35 1.98 x 10 0.58 2.62 x 10 0.77 3.14 x 10 (a) Construct a Beer's law graph for the standard solutions of absorbance versus molar concentration of the cobalt(II) ions. You may use graph paper directly from your laboratory notebook (b) A test solution containing an unknown concentration of cobalt(II) ion was determined to have a transmittance of 35.2%. Using the Beer's law graph for the set of standard solutions, determine the molar concentration of the cobalt(11) ion in the test solution Suppose it was determined in Experiment 398 that 0.610 mol of oxalate ion was present in 100 g of the coordination compound. How many milliliters of 0.500 M CaCl2 would be needed to precipitate the oxalate ion in a 0.100 g sample of the coordination compound? Assume the reaction: Ca?"(aq) + Co. (aq) → CaC2O4(s) 5. What is the purpose of using ascorbic acid in this experiment?