Pre-Lab Questions 1. For the solutions you ill pr epare in Step 2 of Part A, cal

Question

Pre-Lab Questions 1. For the solutions you ill pr epare in Step 2 of Part A, calculate the [FeSNC ]. Presume that all of the SCN ions react. For this section of the experiment, mol SCN calculation of [FeSNC") is: mol FeSCN2. So the mol FeSCN2+ L of total solution Record these values in the data table below and ALSO put your final calculations in your Data Sheet to be used in the experiment. Show your work!! Beaker Number [FeSCN* 0.00 M Blank 2. What steps should you take when using a cuvette? (Cleaning, how to hold them, dire Spectrometer, etc) See your procedure.

Explanation / Answer

The total volume of all the solutions is 50.0 mL.

Note that [Fe3+]/[SCN-] = (0.200 M)/(0.0020 M) = 100; therefore, SCN- is the limiting reactant and hence, the yield of [FeSCN2+] will be decided by [SCN-]. Hence, we need to determine the concentration of SCN-, i.e, [SCN-] for all the solutions.

The concentration of SCN- is obtained as below.

[SCN-] = (0.0020 M SCN-)*(volume of SCN- added in mL)/(total volume of the solution in mL)

[FeSCN2+] = [SCN-]

Take beaker 1 as an example; therefore,

[SCN-] = [FeSCN2+] = (0.0020 M)*(5.0 mL)/(50.0 mL) = 0.00020 M = 2.00*10-4 M.

Beaker

[FeSCN2+]

1

2.00*10-4 M

2

1.60*10-4 M

3

1.20*10-4 M

4

8.00*10-5 M

Blank

0.00 M

Beaker

[FeSCN2+]

1

2.00*10-4 M

2

1.60*10-4 M

3

1.20*10-4 M

4

8.00*10-5 M

Blank

0.00 M

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