Colorimetric Determination for the Composition and Equilibrium Constant For the Formation of a Metal Complex Ion Abstract The object of this experiment was to determine properties for the formation of a metal complex ion, ferrothiocyanate by observing its colorimetric characteristics. The reaction was done for differing amounts of Fe+3 and SCN-, and the absorbance was measured using a spectrophotometer. The absorbance showed that maximum Fe(SCN)+2 ion production was achieved when the mole fraction of SCN was .6, which was close to the expected value of .5. However, when the equilibrium constant was calculated for this reaction, experimental error may have played a role when the achieved value of -660 was significantly different than an expected large positive number. These properties of equilibrium were determined through colorimetric properties. Introduction Colorimetric properties of certain chemical compounds can be used to determine many characteristics of the reaction itself. In this experiment, colorimetric determination was used to find the equilibrium constant for the formation of the Fe(SCN)+2 ion, noted by the equation Fe3+(aq) + SCN- (aq) Fe(SCN)+2 Many chemical reactions such as this reaction are never fully completed in the sense that all the reactants will completely react to form the products. There exists a state known as equilibrium, in which neither the forward reaction nor the reverse reaction is performing. The equilibrium constant, K, is a measurement of the ratio of the concentrations of the reactants to products at which equilibrium is reached- the reaction will neither proceed in the forward nor reverse direction. In this experiment, the equilibrium constant is K= [Fe(SCN)+2] / [Fe... ... middle of paper ... ...esents itself that the actual experiment can’t be completed. If the equilibrium constant were to be calculated accurately, this could be used to calculate concentrations of various products or reactants. This experiment was completed with minor deviations from the original protocol. A slight mistake was made when solutions were transported from the test tube to the cuvette. The funnel wasn’t rinsed out completely, and this may have led to slight deviations. However, it may not have been enough to make a significant impact upon the results. Overall, this experiment went as planned. The equilibrium constant for this reaction was calculated, as well as finding the mole fraction at which this reaction would produce the most significant reaction. Even though some calculations weren’t as expected, this reaction was completed and made sense from a superficial view.
The experiment was not a success, there was percent yield of 1,423%. With a percent yield that is relatively high at 1,423% did not conclude a successful experiment, because impurities added to the mass of the actual product. There were many errors in this lab due to the product being transferred on numerous occasions as well, as spillage and splattering of the solution. Overall, learning how to take one product and chemically create something else as well as how working with others effectively turned out to be a
The complete experimental procedure is available in the General Chemistry Laboratory Manual for CSU Bakersfield, CHEM 213, pages 20-22, 24-25. Experimental data are recorded on the attached data pages.
the replicate shows the same trend as the first experiment. I used a measuring cylinder and a beaker to measure out the amounts of water; however these did not seem to affect the quality of my results. To increase the accuracy of my results I could have perhaps used a burette. Even though I did the best I could to keep the experiment accurate, I did. some places there were mistakes that unintentionally occurred.
Objective: The objective of the experiment is to determine what factors cause a change in speed of a reaction. It is also to decide if the change is correlated with the balanced equation of the reaction and, therefore, predictable. To obtain a reaction, permanganate, MnO_4^(1-), must be reduced by oxalic acid, C_2 O_4 H_2. The balanced equation for the reaction is:
...clear reaction at all. Some think that the process is merely a chemical reaction not yet understood by today’s laws of chemistry. This presents numerous gray areas in the understanding of the reactions taking place in the experiments. If indeed it is a chemical reaction then there is some flaw in our understanding of chemical reactions. The lack of nuclear byproducts when in theory there should be lends strong credence to this belief though. Only continued experimentation and new exploration will help explain the mystery.
Then the reaction tube was capped but not tightly. The tube then was placed in a sand bath reflux to heat it until a brown color was formed. Then the tube was taken out of the sand bath and allowed to cool to room temperature. Then the tube was shaken until a formation of a white solid at the bottom of the tube. After formation of the white solid, diphenyl ether (2 mL) was added to the solution and heated until the white solid was completely dissolved in the solution. After heating, the tube was cooled to room temperature. Then toluene (2 mL) was added to the solution. The tube was then placed in an ice bath. Then the solution was filtered via vacuum filtration, and there was a formation of a white solid. Then the product was dried and weighed. The Final product was hexaphenylbenzene (0.094 g, 0.176 mmol,
A cuvette was filled 3/ 4ths of the way and the absorbance measured in a spectrophotometer. The data was compiled as a class and recorded. The Spectrophotometer was blanked using a test tube of distilled water.
The purpose of this experiment is to use our knowledge from previous experiments to determine the theoretical, actual, and percent yields of the lead chromate from the reaction of solutions of potassium chromate and lead nitrate (Lab Guide pg. 83).
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Varying the n value carries out the experiment. Absorbencies of each of the ZLn complexes are obtained. The sum of the concentrations of the metal, Z, and the ligand, L, are kept equal. With the ratio of the ligand to the metal in the solution with the maximum absorbance for the ZLn complex, the value of n can be determined as well as the composition of ZLn.
The aim of this experiment was to investigate the affect of the use of a catalyst and temperature on the rate of reaction while keeping all the other factors that affect the reaction rate constant.
== Refer to Chemistry Lab # 2 – Investigating Changes. No changes have been made in this experiment. Results = ==
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
If I were to roughly plot a graph for the reaction, it would look like
We have no gases and solids involved, therefore it is easy to deal with solutions. Similarly, the use of a catalyst complicates things, and if used incorrectly could alter the outcome of the experiment. The theory behind this experiment is that increasing the concentration can increase the rate of the reaction by increasing the rate of molecular collisions. GRAPH I will place the reaction mixture on a paper with a black cross drawn on it. When the cross is completely obscured, the reaction will be finished.