The stoichiometry of the reaction was determined in question 2. Once the concent

Question

The stoichiometry of the reaction was determined in question 2. Once the concentration of the complex is known one can determine how much iron (IID and thiocyanide ion are left in the solution. With the three concentrations known equilibrium constants (Kog) can readily be determined. 6. (2 poin) Calculate the equilibrium constant (Kea for solutions numbered 2, 4, and 6. Show your work for full credit 00 coe A Solution 2 [SEMi (conto ouir Fe SCN 0.004 0.00 Solution 4 a .001 CF escN 0.0020 M x 0.001 Fe SCN 001 SCNT Solution 6: Fe KCN at 000A x -CO20 calculate the average value for your equilibrium for solutions 2,3, 4, 5, constant 7. (1 point) and 6).

Explanation / Answer

This is a two part lab. In the first part of the lab, you establish the Beer’s law. For this part, you use a large excess of Fe3+ and make SCN- the limiting reactant. Under these conditions the reaction goes to completion and you have

[SCN-] = [FeSCN2+] (here [SCN-] will denote the initial concentration of SCN-).

You make a series of solutions by varying the amounts of SCN-; then you plot the absorbance (recorded by the spectrophotometer) of Fe(SCN)2+ against [Fe(SCN)2+]. The plot is linear with a relation of the form

y = mx + c where m = slope of the plot = absorptivity of Fe(SCN)2+.

In the second part of the experiment, you use the linear equation from above and plug in the values of absorbance (y = absorbance recorded by the spectrophotometer) and find out x. This x is the [Fe(SCN)2+] at equilibrium. Therefore, to answer your question, I will need the graph or the regression equation from the first part of the experiment.

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