1400 words - 6 pages

Equilibrium

Travis Bland

CHM 2046L

Section 025

April 16, 2014

George Norton

Introduction;

Most chemical reactions are reversible which means that they react both forwards and backwards. A forward reaction is generically A + B -> C + D and a backward reaction is C + D -> A + B. Higher concentrations of A and B at the beginning of the reaction cause it to shift right towards C and D before beginning to slow down as more C and D are created. Eventually, the amount of A and B being formed is the same as the amount of A and B being used, which results in chemical equilibrium, denoted with Keq. From this reaction, the equilibrium constant can be calculated by using the ratio of ...view middle of the document...

Equilibrium Data;

Five clean and dry test tubes are obtained and labeled 1-5. Each is filled with 5.00 mL of 0.002 M Fe(NO3)3 using a burette. Exactly 1.00, 2.00, 3.00, 4.00 and 5.00 mL of 0.00 M KSCN is added to each test tube respectively and enough 0.5 M HNO3 is added to each of the test tubes so the final volume is equal to 10.0 mL. Each test tube is mixed and then the contents are added to a cuvette and tested within a spectrophotometer at 447 nm after calibrating the machine using 0.5 M HNO3.

Results;

Tube Number Volume of .200M Fe(NO3)3 (mL) Volume of .002M KSCN (mL) Volume of .500M HNO3 (mL) Total Volume (mL)

1 2.5 .5 7.0 10

2 2.5 .75 6.75 10

3 2.5 1.0 6.5 10

4 2.5 1.25 6.25 10

5 2.5 1.5 6 10

Tube Number

Concentration of Fe3+ (M) Concentration of SCN- (M) Concentration of Fe(SCN)2+ (M) Absorbencies

0 0 0 0 .000

1 .0500 1.0 x 10-4 1.0 x 10-4 .245

2 .0500 1.5 x 10-4 1.5 x 10-4 .326

3 .0500 2.0 x 10-4 2.0 x 10-4 .845

4 .0500 2.5 x 10-4 2.5 x 10-4 .982

5 .0500 3.0 x 10-4 3.0 x 10-4 1.236

Tube Number

Volume of .002M Fe(NO3)3 (mL) Volume of .002M KSCN (mL) Volume of .5M HNO3 (mL) Total Volume

1 5.0 1.0 4.0 10.0

2 5.0 2.0 3.0 10.0

3 5.0 3.0 2.0 10.0

4 5.0 4.0 1.0 10.0

5 5.0 5.0 0 10.0

Tube Number Initial Concentration of Fe3+ (M) Initial Concentration of SCN- (M) Absorbencies Equilibrium Concentration of Fe(SCN)2+ (M)

1 .001 2.00 x 10-4 .268 3.47 x 10-5

2 .001 4.00 x 10-4 .446 7.58 x 10-5

3 .001 6.00 x 10-4 .546 9.88 x 10-5

4 .001 8.00 x 10-4 .821 1.62 x 10-4

5 .001 10.00 x 10-4 .846 1.67 x 10-4

Fe3+ + SCN- ↔ Fe(SCN)2-

I .001 .0002 0

C -M -M +M

E 9.65 x 10-4 1.65 x 10-4 3.47 x 10-5

Test Tube Number Equilibrium Concentration of Fe3+ (M) Equilibrium Concentration of SCN- (M) Equilibrium Concentration of Fe(SCN)2- (M) Equilibrium Constant (K)

1 9.65 x 10-4 1.65 x 10-4 3.47 x 10-5 217.93

2 9.24 x 10-4 3.24 x 10-4 7.58 x 10-5 253.19

3 9.01 x 10-4 5.01 x 10-4 9.88 x 10-5 218.87

4 8.38 x 10-4 6.38 x 10-4 1.62 x 10-4 303.01

5 8.32 x 10-4 8.32 x 10-4 1.68 x 10-4 242.70

After obtaining an average K value of 245.52, the percent error for the experiment can be calculated using the literature value of 138 and the following equation:

(245.52-138)/138 x 100%=77.9%

Discussion;

In order to obtain the amount of iron nitrate required to perform the experiment, the following equation was used:

(0.2 mol)/(1 L)*1/(1 mol)*(404 g)/1mol*(.02 L)/L=1.616 g Fe(〖NO〗_3...

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