Assignment scoring Your last submission is used for your score. For the followin

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Assignment scoring Your last submission is used for your score. For the following questions absorbance measurements should be reported to three decimal places. Concentrations are from calculations involving the volume (three significant figures) and molarity (three significant figures). If you are having difficulty with the significant figures for the tables in this assignment, try writing out your concentrations in decimal notation. Remember that significant figures can be lost when subtracting values. For example, 1.00e-3 (3sf) 1.53e-4 (3sf) seems like it should give 847e-4 (3sf) However, let's view this with the values written out. A significant figure has been lost because the least precise number, 0.00100, is only good to the hundred thousandths place. Significant Figures. Part A-Calibration curve of FescN2 solutions What is the initial concentration of SCNT in Solution 1A Consider using the formula CVi CM Given your result from the above question. what is the concentration of FescN2 in Solution 1A? Consider the stoichiometry ofthe FescN2* formation reaction. (Enter your result in Table A Table A: Calibration Curve of FeSCNP. Solutions Regression equation y X Part B -Measuring FescN2 in Equilibrium Mixtures Supporting Materials Periode Table

Explanation / Answer

For the reaction,

Fe3+ + SCN- <==> [FeSCN]2+

Part A)

Initial concentration of [SCN-] in solution

Using,

Initial concentration (C2) = C1V1/V2

For 1A,

C1 = 5 x 10^-4 M (initial concentration of SCN- solution taken)

V1 = 1 ml (volume of SCN- taken)

V2 = 12 ml (total volume of solution)

So,

initial concentration of [SCN-] (C2) = 5 x 10^-4 M x 1 ml/12 ml

                                                        = 4.16 x 10^-5 M

Similarly,

For 2A,

C1 = 5 x 10^-4 M (initial concentration of SCN- solution taken)

V1 = 1.5 ml (volume of SCN- taken)

V2 = 12 ml (total volume of solution)

So,

initial concentration of [SCN-] (C2) = 5 x 10^-4 M x 1.5 ml/12 ml

                                                        = 6.25 x 10^-5 M

For 3A,

C1 = 5 x 10^-4 M (initial concentration of SCN- solution taken)

V1 = 2 ml (volume of SCN- taken)

V2 = 12 ml (total volume of solution)

So,

initial concentration of [SCN-] (C2) = 5 x 10^-4 M x 2 ml/12 ml

                                                        = 8.33 x 10^-5 M

For 4A,

C1 = 5 x 10^-4 M (initial concentration of SCN- solution taken)

V1 = 2.5 ml (volume of SCN- taken)

V2 = 12 ml (total volume of solution)

So,

initial concentration of [SCN-] (C2) = 5 x 10^-4 M x 2.5 ml/12 ml

                                                        = 1.04 x 10^-4 M

For 5A,

C1 = 5 x 10^-4 M (initial concentration of SCN- solution taken)

V1 = 3 ml (volume of SCN- taken)

V2 = 12 ml (total volume of solution)

So,

initial concentration of [SCN-] (C2) = 5 x 10^-4 M x 3 ml/12 ml

                                                        = 1.25 x 10^-4 M

Here, [SCN-] is the limiting reagent,

So, [FeSCN]2+ = [SCN-]

Find absorbance for each solution

Plot absorbance versus [FeSCN]2+ concentration

From the graph,

slope = molar absorptivity for [FeSCN]2+

Part B) use molar absorptivity to calculate [FeSCN]2+eq in each solution

[FeSCN]2+eq = absorbance/molar absorptivity

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