A lab experiment to determine the concentration of an unknown solution by colorimetry

Semester 1 SMBB This course encompasses the basic principles and techniques involved in molecular biology which will enable students to apply these techniques in the genetic engineering laboratory. The introductory lecture will expose students to genetic engineering and its application in various sectors of the industry such as agriculture, medical, pharmaceutical, environmental, etc. The following lectures will revolve around techniques in genetic engineering, cloning of heterologous genes in the Escherichia coli host which will include common procedures in molecular biology, enzymes important in molecular biology, plasmids and bacteriophage as cloning vectors, gene libraries preparation and screening for gene of interest. Before semester ends, students are to produce a group poster relevant to genetic engineering as a form of teamworking experience.

A lab experiment to determine the concentration of an unknown solution by colorimetry

Overview[ edit ] Spectrophotometry is a tool that hinges on the quantitative analysis of molecules depending on how much light is absorbed by colored compounds. Spectrophotometry uses photometersknown as spectrophotometers, that can measure a light beam's intensity as a function of its color wavelength.

Important features of spectrophotometers are spectral bandwidth the range of colors it can transmit through the test samplethe percentage of sample-transmission, the logarithmic range of sample-absorption, and sometimes a percentage of reflectance measurement.

A spectrophotometer is commonly used for the measurement of transmittance or reflectance of solutions, transparent or opaque solids, such as polished glass, or gases.

Although many biochemicals are colored, as in, they absorb visible light and therefore can be measured by colorimetric procedures, even colorless biochemicals can often be converted to colored compounds suitable for chromogenic color-forming reactions to yield compounds suitable for colorimetric analysis.

A certain chemical reaction within a solution may occur in a forward and reverse direction, where reactants form products and products break down into reactants.

At some point, this chemical reaction will reach a point of balance called an equilibrium point. In order to determine the respective concentrations of reactants and products at this point, the light transmittance of the solution can be tested using spectrophotometry.

The amount of light that passes through the solution is indicative of the concentration of certain chemicals that do not allow light to pass through.

A lab experiment to determine the concentration of an unknown solution by colorimetry

The absorption of light is due to the interaction of light with the electronic and vibrational modes of molecules.

Each type of molecule has an individual set of energy levels associated with the makeup of its chemical bonds and nuclei, and thus will absorb light of specific wavelengths, or energies, resulting in unique spectral properties.

The use of spectrophotometers spans various scientific fields, such as physicsmaterials sciencechemistrybiochemistryand molecular biology. Spectrophotometry is often used in measurements of enzyme activities, determinations of protein concentrations, determinations of enzymatic kinetic constants, and measurements of ligand binding reactions.

In astronomythe term spectrophotometry refers to the measurement of the spectrum of a celestial object in which the flux scale of the spectrum is calibrated as a function of wavelengthusually by comparison with an observation of a spectrophotometric standard star, and corrected for the absorption of light by the Earth's atmosphere.

Beckman in [ disputed — discuss ], the spectrophotometer was created with the aid of his colleagues at his company National Technical Laboratories founded in which would become Beckman Instrument Company and ultimately Beckman Coulter.

This would come as a solution to the previously created spectrophotometers which were unable to absorb the ultraviolet correctly. He would start with the invention of Model A where a glass prism was used to absorb the UV light. It would be found that this did not give satisfactory results, therefore in Model B, there was a shift from a glass to a quartz prism which allowed for better absorbance results.

COLORIMETRIC ANALYSIS | Mark Buluma Eugine - srmvision.com

From there, Model C was born with an adjustment to the wavelength resolution which ended up having three units of it produced. The last and most popular model became Model D which is better recognized now as the DU spectrophotometer which contained the instrument case, hydrogen lamp with ultraviolent continuum and a better monochromator.

In the words of Nobel chemistry laureate Bruce Merrifield said it was "probably the most important instrument ever developed towards the advancement of bioscience.

It irradiates the sample with polychromatic light which the sample absorbs depending on its properties. Then it is transmitted back by grating the photodiode array which detects the wavelength region of the spectrum. Design[ edit ] Single beam scanning spectrophotometer There are two major classes of devices: A double beam spectrophotometer [13] compares the light intensity between two light paths, one path containing a reference sample and the other the test sample.

A single-beam spectrophotometer measures the relative light intensity of the beam before and after a test sample is inserted. Although comparison measurements from double-beam instruments are easier and more stable, single-beam instruments can have a larger dynamic range and are optically simpler and more compact.

Additionally, some specialized instruments, such as spectrophotometers built onto microscopes or telescopes, are single-beam instruments due to practicality.

Spectrophotometry - Wikipedia

Historically, spectrophotometers use a monochromator containing a diffraction grating to produce the analytical spectrum. The grating can either be movable or fixed.

If a single detector, such as a photomultiplier tube or photodiode is used, the grating can be scanned stepwise scanning spectrophotometer so that the detector can measure the light intensity at each wavelength which will correspond to each "step".

Arrays of detectors array spectrophotometersuch as charge coupled devices CCD or photodiode arrays PDA can also be used. In such systems, the grating is fixed and the intensity of each wavelength of light is measured by a different detector in the array.

Additionally, most modern mid-infrared spectrophotometers use a Fourier transform technique to acquire the spectral information.


This technique is called Fourier transform infrared spectroscopy. When making transmission measurements, the spectrophotometer quantitatively compares the fraction of light that passes through a reference solution and a test solution, then electronically compares the intensities of the two signals and computes the percentage of transmission of the sample compared to the reference standard.In physical and analytical chemistry, colorimetry or colourimetry is a technique "used to determine the concentration of colored compounds in solution." [1] A colorimeter is a device used to test the concentration of a solution by measuring its absorbance of a specific wavelength of light (not to be confused with the tristimulus colorimeter.

Lesson 4: Colorimetry.

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One useful and often used way of determining the concentration of a chemical in a solution, if it has a color, is to measure the intensity of the color and relate the intensity of the color to the concentration of the solution. Prospective inbound mobility students can browse through the list of undergraduate courses available at UTM for the UTM Student Exchange Program below.

The purpose of this experiment was to study the absorbance of CuSO molar absorptivity could be used to determine the concentration of unknown # The absorbance of the undiluted solution was much higher () than the M standard solution.

This resulted in a diluted solution with an absorbance of Using Beer's Law, the. The purpose of this experiment is to conclude the concentration of an unknown solution using colorimetry to plot a calibration curve. Colorimetry measures the absorption of light at wavelengths within the visible region of the electromagnetic spectrum.

The primary objective of this experiment is to determine the concentration of an unknown nickel (II) sulfate solution. You will be using the Colorimeter shown in Figure 1.

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