Preview

Analysis Of The Beer-Lambert Law For Kmno4

Better Essays
Open Document
Open Document
1325 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Analysis Of The Beer-Lambert Law For Kmno4
Introduction Objectives Validate the Beer-Lambert law for KMnO4. To determine the pKa for an acid-base indicator To estimate the equilibrium constant for the formation of complex ion Fe(NSC)²ꭞ The function of part two of the experiment is to find the value of the constant K, in the following equilibrium constant: K=[Fe (NSC) ²⁺]/ [Feᶟ⁺] [NCS⁻], while not disrupting the equilibrium.

Theory
For part one. The majority of chemical compounds are known to absorb UV or visible light. Depending on the nature of the electronic transitions involved determine the wavelengths absorbed. The concentration of the compound present in a sample determine the intensity of light absorbed. Many compounds absorb very strongly we can therefore monitor
…show more content…
Starting with a 4X10⁻⁴M KMNO₄ stock solution, dilute the stock to prepare the following four solutions using clean, dry test tubes:
4x10⁻⁴M, 2x10⁻⁴M, 1x10⁻⁴M and 0.5x10⁻⁴M and measure the absorbance of each solution, respectively. Use a spectrometer to determine the absorbance of each sample. Cuvettes are placed in the cells. Rinse the cuvette with deionised water and then with the solution it will contain to avoid experimental error and an inaccurate reading of the absorbance. Fill cuvette to approx. 3/4. Be sure to adjust the machine to zero absorption. Note that KMnO4 has maximum at a wavelength of 524nm, a baseline test using deionised water is run for wavelengths in the range 500nm-550nm. Start with the most dilute samples placing water in the first cell and add samples anticlockwise in order of increasing concentration. Ensure all axes are labelled, graph has a title and note the units. Once results are obtained, plot a graph with concentration on the x-axis and absorbance on the y-axis (absorbance vs concentration).
Determine the concertation of the unknown solution provided using your
…show more content…
Incorrect decontaminant procedure for cuvette: not washing with deionised water and then the solution it will contain.
While all the results did not verify the Beer- Lambert law, there is correlation between the results for the absorbance for 4x10⁻⁴ of Potassium Permanganate which is .931 and 2x10⁻⁴ which is .427. We can see evidence of the Beer – Lambert law, as the difference between the two absorbance values is 0.5063, which is approximately 1/2, which are expected results.
These errors also apply to part two of the experiment: Determination of the Equilibrium Constant of [Fe (NCS)] ²⁺ as the absorbance values for [Fe (NCS)] ²⁺ are also not obeying the beer- lambert law. This means that for future experimentation, techniques of accuracy and precision must be applied strictly and carefully, to ensure results are represented as accurately as possible, with minimum experimental error. It is clear that the errors in this experiment are systematic, as errors are consistent and the procedure was wrongly carried out by the experimenters.

You May Also Find These Documents Helpful

  • Good Essays

    6. To each tube, carefully add 2 mL of the KMnO4 solution. Shake the mixture carefully.…

    • 732 Words
    • 3 Pages
    Good Essays
  • Powerful Essays

    The purpose of this lab was to calculate the equilibrium constant for the reaction of iron (III) ions with thiocyanate ions.…

    • 1137 Words
    • 8 Pages
    Powerful Essays
  • Powerful Essays

    Chem 103 Project Lab

    • 1372 Words
    • 6 Pages

    Beer’s Law helps explain the relationship between absorbance and thickness off a sample, and accordingly, the relationship between absorbance and the amount of solute in a solution. Forming a Beer’s Law plot is useful when having a solution…

    • 1372 Words
    • 6 Pages
    Powerful Essays
  • Good Essays

    Tube 2 Lab Report

    • 603 Words
    • 3 Pages

    As indicated by the figure, the high concentration correlated to having the highest amount of absorbance (1.006 at 300 seconds). This was followed by the medium-high concentration (0.555) and medium concentration (0.540). It can be noted that the medium concentration started off with a higher absorbance than the medium-high concentration, but the medium-high concentration had a faster increase of absorbance over time. Thus, surpassing the absorbance of the medium concentration from 270 and 300 seconds. The low concentration had the lowest amount of absorbance, with a final absorbance rate of 0.204, and did not substantially increase over the period of…

    • 603 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Absorbance is defined as a measure of the capacity of a substance to absorb light of a specified wavelength. Concentration is defined as the amount of solute per unit volume of solution. Beer’s law is defined as a method that relates the absorption of light to the properties of the material through which one substance like light is traveling. Calibration Curve is defined as a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration.…

    • 556 Words
    • 4 Pages
    Good Essays
  • Powerful Essays

    Red 40 Lab

    • 2090 Words
    • 9 Pages

    Determining Red 40 Concentrations Using Absorption with Beer’s Law Introduction I like color and enjoyed learning about wavelengths and the spectrum of light, so I considered incorporating something related to that into my Internal Assessment. We also had just used concentrations in our Group 4 Project, so when I found an experiment that dealt with both of these I thought it was a great idea. This experiment is not completely original; the basic concept has been used multiple times. It uses Beer’s Law: · A is light absorbance · is “molar absorptivity with units of L mol-1 cm-1” · l is the length of the cuvette in centimeters · c is the concentration of the solution in mol L-1…

    • 2090 Words
    • 9 Pages
    Powerful Essays
  • Good Essays

    In order to complete the objective, the group used a Carolina Digital Spectrophotometer, unit M 201-1, which measures the quantity of light that solutions absorb. The spectrophotometer consists of a light source that shines through a prism which then shines through a…

    • 1159 Words
    • 5 Pages
    Good Essays
  • Better Essays

    Beers Law

    • 879 Words
    • 4 Pages

    The purpose of this experiment is to apply Beer’s Law by analyzing samples provided by Q laboratory to determine their absorbance and prepare a Beer’s law plot. Molarity of these samples was also calculated to determine concentration and percent error rate. Students also analyzed the concentration of blue dye #1 to determine the concentration of blue dye #1 in a commercial blue dye drink.…

    • 879 Words
    • 4 Pages
    Better Essays
  • Better Essays

    Bio Spectroscopy Lab

    • 1273 Words
    • 6 Pages

    This investigation used spectroscopy to evaluate light absorption in different solutions. A spectrophotometer was used in the lab to determine these values. A spectrophotometer is an apparatus used to “measure the absorption of radiation in the visible and UV regions of the spectrum and allows precise at a particular wave length” (Jones et al., 2007). The amount of light absorbed by a substance is directly in relation to the concentration of the solute and also the wavelength moving through the solute (Jones et al., 2007). This is commonly referred to as Beer’s Law and can be expressed as A= εl [C]. Beer’s Law equation measures the absorbency of light, making it an effective measure as spectrophotometers give exact values for absorbency (Jones et al., 2007).…

    • 1273 Words
    • 6 Pages
    Better Essays
  • Satisfactory Essays

    Carefully pour the potassium nitrate solution down the sink with plenty of water and clean your equipment.…

    • 482 Words
    • 2 Pages
    Satisfactory Essays
  • Better Essays

    protocal

    • 987 Words
    • 4 Pages

    1. To understand how spectrophotometry can be used to determine the concentration of a light-absorbing substance.…

    • 987 Words
    • 4 Pages
    Better Essays
  • Good Essays

    Chemical Equilibrium Lab

    • 534 Words
    • 3 Pages

    Although we prepared five different equilibrium solutions, each having different concentrations, the equilibrium constant KC for each of the reactions had similar values. By calculating the average and comparing each of the values to the average there was a percent error of _____.…

    • 534 Words
    • 3 Pages
    Good Essays
  • Best Essays

    The UV/Vis spectrophotometer work by passing the light by strong lamp through a monochromator, which split the light into its component colours using a gratings. Then, the desired wavelength of light beam is direct through the sample compartment which the cuvette is placed by using the mirror and slit. At other side of the compartment, there is a detector which can determine the amount of light beam pass through the solution in the cuvette, thus the absorbance of the solution in the cuvette can be determined. In addition, the absorbance of light is determined by three factors which is the nature of the solution, concentration of the solution, and the distance of light travel through the solution (path length) which stated in the Beer-Lambert Law.…

    • 2163 Words
    • 9 Pages
    Best Essays
  • Satisfactory Essays

    Fe(SCN)2, which was found to be 1.942 x 10-3 M-1cm-1. Given the molar absorptivity and absorbance,…

    • 383 Words
    • 2 Pages
    Satisfactory Essays
  • Powerful Essays

    Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This measurement can also be used to measure the amount of a known chemical substance. Spectrophotometry is one of the most useful methods of quantitative analysis in various fields such as chemistry, physics, biochemistry, material and chemical engineering and clinical applications.…

    • 1686 Words
    • 7 Pages
    Powerful Essays