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Equilibrium Lab

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Isabella Kup

on 5 August 2015

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Transcript of Equilibrium Lab

Equilibrium Lab
Calculations & Results
Conclusion
Introduction
Chemical Equilibrium:

Calculations & Results
References
Calculating_Equilibrium_Constants. Calculating_Equilibrium_Constants.
N.p., n.d. Web. 04 Aug. 2015.

Spectrophotometry. : Basic Principles. N.p., n.d. Web. 04 Aug. 2015.

SBU Chemistry Intro Lab - Beer's Law. SBU Chemistry Intro Lab - Beer's Law.
N.p., n.d. Web. 04 Aug. 2015.

Molecular Spectroscopy. Beer-Lambert Law. N.p., n.d. Web. 03 Aug. 2015.

Sandi, Santiago et al. General Chemistry 2 Laboratory Manual. Tampa: Pro-
Copy, 2015. Print.


Methods
To begin the lab five clean and dry test tubes were obtained and labeled 1-5. Each was filled with 2.50 mL of 0.200 M Fe(NO3)3. To test tube #1 exactly 0.50 mL of 0.00200 M KSCN solution was added and to test tube #2 0.75 mL of 0.00200 M KSCN solution was added and so on in increments of 0.25 mL. Next enough 0.5 M HNO3 was added to each of the test tubes so that the final volume in each tube totals 10.00 mL. The tubes were covered and inverted numerous times until the contents were well mixed.

The spectrophotometer was set to 447 nm and was zeroed with a cuvet filled with 0.5 M HNO3. The contents of test tube #1 was poured into a cuvet and placed into the spectrophotometer. The absorbance level was recorded and this process was repeated for test tubes 2-5.

Five clean and dry test tubes were obtained and each was filled with 5.00 mL of 0.00200 M Fe(NO3)3. If a test tube is wet, rinse it several times with small portions of the solution. Exactly 1.00, 2.00, 3.00, 4.00, and 5.00 mL of 0.00200 M KSCN was added, respectively, to test tubes labeled 1, 2, 3, 4, and 5. To finish the solutions enough 0.5 M HNO3 was added to each of the test tubes so that the final volume in each tube totaled 10.00 mL. The tubes were covered and inverted numerous times until the contents were well mixed. The temperature of one of the samples was recorded and the samples were run through the spectrophotometer the same way as they were before and the absorbance for each of the samples was recorded.

Once everything was cleaned and disposed of properly then calculations were performed for the standard curve and concentration data and ICE tables were constructed.
Calculations & Results
Discussion
Calculations & Results
Calculations & Results
During this experiment, the students worked together to find the equilibrium constant of the solutions created. As the students used different concentrations of KSCN on each test tube, they expected the equilibrium constants to follow that same pattern. As seen in the results, the group discovered the concentrations as predicted.
The group struggled in the beginning of the experiment with figuring out how to use the spectrophotometer as they at first didn't have one, then the one they had did not work. Once that problem was solved, everything worked smoothly.
During the second round of solutions, the students found that the results were not as predicted and they decided to make other solutions just in case there was a mistake, then they got the results expected.
Making the ICE tables and interpreting the results found was by far the hardest part of the experiment but, the students worked together and interpreted the results accordingly.
In future experimentation, the group should try to work more slowly as to avoid mistakes and achieve more accurate results.
A balanced condition in which a system breaks down and forms substances at the same rate
At equilibrium the number of molecules becomes definite and constant.
Equilibrium Constant:
The ratio of concentrations when reaction reaches equilibrium.
Intro Cont.
The purpose of this project was to determine the equilibrium constant for metals with ligand (usually donates electrons) molecules that result in intensely colored products.
Fe3+ and its ligand thiocyanate SCN-.
Spectrophotometry
The method used to measure how much a chemical substance absorbs light by measuring the intensity of light as it passes through a sample solution

(each compound absorbs or transmits light over a certain range of wavelength).
An equation was developed using absorbance vs concentration
While using the spectrophotometer it was clear that increasing the concentration would increase the absorbance.
As light passes through the sample of material, the photons of light hit the molecules of the substance and dissipate The higher the concentration, the more likely it is for the light to hit a molecule, thus giving the substance a darker color.
The average equilibrium constant was 474.76, because it is greater than one, at equilibrium, the reaction favor the formation of products.
K>1 reaction favors products
Beer's Law
Isabella Kup
Jena Pecori
Christopher Cruz
Eric Mubang
Full transcript