1) Dilute your sample again.. For r malachite green: take 5 ml and dilute to 250
ID: 568485 • Letter: 1
Question
1) Dilute your sample again.. For r malachite green: take 5 ml and dilute to 250 mL with a second volumetric flask or crystal violet: take 5 ml and dilute to 100 ml with a second volumetric flask 2) Use the Logger Pro program on the laptops provided to determine your absorption. a) Add deionized water to a cuvette and make sure to wipe the sides of the cuvette prior to placing it in the instrument. b) Go to the dropdown menu under experiment to the calibrate choice. Select calibrate & click on it (It takes about 90 seconds). Once your instrument is calibrated, you can take a second cuvette and add your solution to it. Wipe off the sides with a chem wipe and insert it in the instrument. c) d) After the cuvette is inserted, hit "collect." The spectra doesn't take too long to appear e) Record the absorption value that is the highest. For malachite green, the wavelength to check is around 616.5. (This is ideally where the strongest absorption occurs). For crystal violet, the wavelength to check is around 590. (Again, where the strongest absorption should occur). Print the spectra (or take a picture if the printer doesn't work). f) 3) Once you have your absorption, use it to calculate the concentration using Beer's Law. For A-Ebc you have all values except "c" at this point. Solve for "c" and you will have the concentration in mol/L A Absorbance E epsilon coefficient (different for each one, see below) B cell path length (1 cm) c-concentration in mol/L Epsilon coefficients Malachite Green: 148900 M-1 cm-1 Crystal Violet: 92700 M-1 cm-1Explanation / Answer
1) For the dilution from the 25 mL volumetric flask
Take 1 mL of malachite green into 25 mL volumetric flask and dilute up to 25 mL. In other words, take 1 mL of malachite green and add 24 mL of solvent for dilution.
2) Cuvette or qartz cuvette is the glassware that is used into absorption reader.
3) The theoretical wavelength is 616.5 nm where the strongest absorption occurs.
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