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Table 2: Data Table for Reaction. FeSCN AcMC (C4500) 2 Absorbance 0.103 2 Equili

ID: 1034399 • Letter: T

Question

Table 2: Data Table for Reaction. FeSCN AcMC (C4500) 2 Absorbance 0.103 2 Equilibrium Molarity of FeSCN 2.29e-5 4.8e-5 7.87e-5 9.02e-5 1.214 1.00e-3 1.00e-3 1.00-3 1.00e-3 1.00e-3 4Initial Molarity of SCN 2.00e-4 4.00e-4 6.00e-4 8.00e-4 1.000-3 5Equilibrium molarity Fe9.77e-4 9.52e-4 9.21e-4 9.10e-4 8.79e-4 6Equilibrium Molarity of SCN 1.98e-3 3.52e-4 5.21e-4 7.10e-4 8.79e-4 114.5 143.24 164.01139.61 156.61 Kc Average Ke 143.59 Table 3: Data Table for Reaction: Fe an +2 SCNo)Fe(SCN 0.103 0.216 0.354 0.406 0,546 Absorbance 2 Equilibrium Molarity of Fe(SCN)2 3Initial Molarity of Fe 4Initial Molarity of SCN Equilibrium molarity Fe 6 Equilibrium Molarity of SCN Kc Average Kc

Explanation / Answer

The relation between absorbance and molarity is given as

A = MC where C is a constant and is equal to 4500 M-1 and M denotes the molarity of the solution.

We shall assume that the initial concentrations of Fe3+ and SCN- are the same as in table 1.

1

2

3

4

5

1

Absorbance

0.103

0.216

0.354

0.406

0.546

2

Equilibrium Molarity of [Fe(SCN)2+] = A/C = Absorbance/4500

2.29*10-5

4.80*10-5

7.87*10-5

9.02*10-5

1.21*10-4

3

Initial Molarity of Fe3+

1.00*10-3

1.00*10-3

1.00*10-3

1.00*10-3

1.00*10-3

4

Initial Molarity of SCN-

2.00*10-4

4.00*10-4

6.00*10-4

8.00*10-4

1.00*10-3

5

Equilibrium Molarity of Fe3+ = (initial molarity of Fe3+) – (equilibrium molarity of [Fe(SCN)2+])

9.77*10-4

9.52*10-4

9.21*10-4

9.10*10-4

8.79*10-4

6

Equilibrium molarity of SCN- = (initial molarity of SCN-) – (equilibrium molarity of [Fe(SCN)2+])

1.77*10-4

3.52*10-4

5.21*10-4

7.10*10-4

8.79*10-4

7

Kc = [Fe(SCN)2+]/[Fe3+][SCN-]2

7.48*105

4.07*105

3.15*105

1.97*105

1.78*105

8

Average Kc

3.69*105

1

2

3

4

5

1

Absorbance

0.103

0.216

0.354

0.406

0.546

2

Equilibrium Molarity of [Fe(SCN)2+] = A/C = Absorbance/4500

2.29*10-5

4.80*10-5

7.87*10-5

9.02*10-5

1.21*10-4

3

Initial Molarity of Fe3+

1.00*10-3

1.00*10-3

1.00*10-3

1.00*10-3

1.00*10-3

4

Initial Molarity of SCN-

2.00*10-4

4.00*10-4

6.00*10-4

8.00*10-4

1.00*10-3

5

Equilibrium Molarity of Fe3+ = (initial molarity of Fe3+) – (equilibrium molarity of [Fe(SCN)2+])

9.77*10-4

9.52*10-4

9.21*10-4

9.10*10-4

8.79*10-4

6

Equilibrium molarity of SCN- = (initial molarity of SCN-) – (equilibrium molarity of [Fe(SCN)2+])

1.77*10-4

3.52*10-4

5.21*10-4

7.10*10-4

8.79*10-4

7

Kc = [Fe(SCN)2+]/[Fe3+][SCN-]2

7.48*105

4.07*105

3.15*105

1.97*105

1.78*105

8

Average Kc

3.69*105