Analytical Chemistry for Technicians, Lab Report Example

Stoichiometry 2: Stoichiometry of an Iron (III) – Phenol Reaction

Objective: A spectrometer will be applied in order to calculate the quantity of substrate produced when Fe (NO₃)₃reacts with phenol

Introduction

The spectrometer will be utilized in the laboratory experiment in order to calculate the quantity of a substrate that is produced when the iron (III) nitrate engages in a reactionwiththe solution of phenol derivate.  This reaction will be reviewed by applying a varying concentration in the 5 – sulfosaliccyclic acid and the iron (III). The magnitude of the characteristic of color intensity that is the outcome of the reaction will be applied in order to calculate the stoichiometry proportion. . The characteristic of color intensity of the solution should be able to be differentiated by eyesight. However, in order to apply empirical processes a spectrometer will be used in order to compute the color spectrum of intensities.

The experiment will be conducted in order to determine the molar proportion of Iron (III) and 5- sulfosalicylic acid. The purpose of the experiment will also be to examine the formulas that are applied in order to calculate absorbance and transference of light

Aspirin is a part of the salicylate group of chemical. The chemical has the ability of being converted by the digestive system subsequent to a transformation. Salicylic acid can cause irritation due to its attribute of being an acid. The 5 sulfosalicycic acid is more readily digested.

Materials

A spectrometer was applied. In addition, a Mohr pipette that had a 10 ml capacity was used. A rubber bulb was applied. Nineteen of the 18 x 150 mltesting tubes were implemented. Labels and marking pens were applied in order to distinguish the testing tubes. The amount of 1.7 x 10^{3 M} of Fe (NO₃)₃ that was in a 0.1 M HNO₃ solution was implemented.  The experiment also applied 1.7 x 10³ M of 5- sulfosalicylic acid that was in a 0.1 M HNO₃ solution.

Procedure

The nineteen 18 x 150 ml testing tubes were labelled from one to nineteen. These testing tubes were established in a numbered order andpositioned in the test tube rack. Each of the testing tubes was filled with 100 ml of the 5 – sulfosalicylic acid solutions and the iron (III) nitrate solutions. The proportions of the 5-sulfosalicylic acid and the iron (III) nitrate were documented. A rubberbulb was applied   in order to safely apply suction in order to fill the testing tubes. All of the solutions were preparedprior to applying the spectrophotometer.

A sterile stirring rod was applied in order to combine the contents of each of the testing tubes. Care was taken in order to desiccate the stirringrod prior to agitating the subsequent solution. The testing tubes were allowed to settle with their contents for fiveminutes in order to enable the outcome of the reaction to fully develop. The test tubes wereexamined in order to determine which possessed the deepest violet hue.

The spectrometers were applied in order to empirically analyze each of the testing tubes.  The qualities of the light absorbance and the light transference were examined. The measurements were performed rapidly in order to avoid any possibledrift. The data was transcribed to the most approximate 0.1% unit of transmittance.

Discussion

The 5- sulfosalicylic acid develops a salicylic ion, when water is added as a solvent causes the substance to convert into the acid solution that can be combined with Fe (NO₃)₃. This combination that occurs in a one to one proportion causes the development of a complex that is an iron (III) complex that manifests a robust violet color. The quality of the violet color is perceived as a result that the complex has the ability of absorbing green light. As the green light is separated from the conventional white light spectrum, the violet light can be examined. The ability of absorbing the green light can be applied in order to ascertain how much aspirin is found in the solution. The greater the amount of green light that can be absorbed, the greater the violet quality of the solution becomes. As a result of the elevated absorption of green light, the greater the amount of salicylic acid that is encountered in the solution.

The chemical relationship that is demonstrated between the characteristics of absorbance (A) and transference (T) can be detailed by the amount of light that is absorbed and that is transferred through the sample. This relationship is detailed as the Beer- Lambert law that is expressed as A= a b c.  In this formula, a is the light absorbance of the solution, b is the distance travelled by the light during the length of the testing tube and c is the molar saturation of the solution that is being evaluated (Kenkel 194).

Conclusion

Graphically the laboratory experiment concurred with the results. Testing tube number ten was determined to have the optimal solution that facilitated the best chemical reaction between the Fe (NO₃)₃and the 5 sulfosalicylic acid. The results were proven to be what had been anticipated. The potential sources of error could have been the light transference of the spectrometer which had a margin of uncertainty of ± 0.1% and the testing tubes that had a margin of uncertainty of ± 1 ml.

Works Cited

Kenckel, John. Analytical chemistry for technicians (third edition). Boca Raton, FL: CRC Press, 2002. Print.