Crystal violet, also known as Gentian Violet, is a dye commonly used in laboratory settings for a variety of purposes. It is known for its ability to stain cells and tissues, and is often used to visualize and differentiate between different types of cells or microorganisms.
One common use of crystal violet in the laboratory is in the Gram stain, a technique used to identify bacterial species. The Gram stain involves applying crystal violet to a sample of bacteria, followed by the application of a decolorizing solution and then a counterstain. The result is that some bacteria will appear purple or blue, indicating that they are Gram-positive, while others will appear red or pink, indicating that they are Gram-negative.
Crystal violet can also be used to stain tissues and cells in histological preparations. In this application, the dye is applied to a tissue section on a microscope slide and allowed to penetrate the cells. The tissue is then washed and counterstained with a contrasting dye, such as eosin. This allows for the visualization of different cell types and structures within the tissue, as well as any abnormal or pathological changes.
In addition to its use in microscopy, crystal violet can also be used to identify and quantify microorganisms in water and other environmental samples. By adding the dye to a sample and then measuring the absorbance of the resulting solution at a specific wavelength, it is possible to determine the concentration of microorganisms present. This technique is known as the crystal violet assay.
Overall, crystal violet is a versatile and widely used dye in the laboratory setting, with applications ranging from the identification and classification of bacteria to the visualization of cells and tissues under the microscope. Its ability to stain a range of biological materials makes it an important tool in many areas of scientific research and diagnosis.
Retrieved 12 July 2019. The process is then repeated, isolating each of the other reactants in turn, until all of the orders have been determined. The amount of CV+ ions does significantly drop as the reaction proceeds. Reaction of crystal violet with OH —. Experimental Upon arrival in class you will be assigned hydroxide concentrations either 0. The Sigma-Aldrich Handbook of Stains, Dyes, and Indicators.
Introduction Crystal violet is a common, beautiful purple dye. Recall that absorbance for a specific concentration of a solution with a fixed path length varies directly with the absorptivity coefficient of the solution. Each group will measure the absorbance of CV as a function of time at a different assigned hydroxide concentration using an Ocean Optics spectrometer. The reaction of cellulose and oxygen is spontaneous, but you need to initiate the combustion by adding activation energy from a lit match. Explain this observation in terms of each item below.
Crystal violet will stain skin and clothing! Recall that the value of k is temperature dependent. Use the tip of the temperature probe to stir the mixture. The sum of the individual orders is the overall order of the reaction. So, the rate law for this reaction can be written as shown in Eqn. Rinse a cuvette three times with small portions of the reaction mixture and fill the cuvette three-quarters full with the reaction mixture.
The chromophore groups are responsible for reflecting light and give the molecule its characteristic color. Using this relationship, concentration and absorbance may be calculated if one variable is known while keeping ε and b constant. In strongly basic solutions, the bright color of the dye slowly fades and the solution becomes colorless. Do this multiple times and calculate the average. . Experimental Determination of a Rate Law. Push the Collect button to start the kinetics run.
Do not throw away your hydroxide or CV solutions until you have prepared all three graphs for all three runs. Save the absorption spectrum to print later from Excel and include in your notebook. Multiply the concentration at time zero by 0. Do not adjust any of the spectrometer settings during a kinetics run; it will ruin your data. Once the trial is finished, discard the reaction mixture into the sink, thoroughly rinse the cuvette. Record the concentration of CV it should be around 2 x 10 -5 M. If you are comparing different cell lines, I would count time from the time you seeded them.
This relationship is known as Beer's Law. This allows for the calculation of k, by setting up the following equation: 6. Adjust the diluted fold according to the linear range of standard curve. The relationship between k obsand the intrinsic rate constant, k, for this reaction is given by Eqn. Plot the absorbance of CV+ on the y-axis of the first graph. PDF from the original on 8 August 2014.
While the thermodynamics and kinetics of a reaction may at times seem complementary, and at other times seem contradictory, it is always important to have a detailed understanding of both. In this experiment you will investigate the reaction of crystal violet with sodium hydroxide. Conclusions The conclusion should use the outline for a Use Tables 2 as a model for your Summary Table. If you want to use 24-well plates just adjust the volumes of staining and lysing solutions accordingly. Retrieved 24 July 2014. The positive charge shown on the central carbon atom in figure 1a is delocalized via resonance to the three nitrogen atoms.
It can also be determined by looking at the plot of the data and seeing which order yields a straight line. Before repeating the experiment, chill the reagents in an ice bath. Procedure: 6 solutions were created, based on various concentrations of stock solution, to measure absorbance values at 565 nm. The process of Chemistry of Crystal Violet Crystal violet belongs to a class of intensely colored organic compounds called triphenylmethane dyes. The differential rate law can be integrated to link changes in concentration with time as opposed to rate.