When do you need to blank a spectrophotometer (Spec 20)?After completing all data collection.After the wavelength is changed.Before running a set of samples.Between each sample, even if the wavelength remains the same.

Answer - Before running a set of sample. Spectrophotometer :- Spectrophotometer is tool used…

Answered: When do you need to blank a…

Living by Chemistry

2nd Edition

ISBN:9781464142314

Author:Angelica M. Stacy

Publisher:Angelica M. Stacy

ChapterU5: Fire: Energy , Thermodynamics, And Oxidation-reduction

SectionU5.116: How Absorbing: Spectroscopy

Problem 6E

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When do you need to blank a spectrophotometer (Spec 20)? a.After the wavelength is changed. b.After completing all data collection. c.Before running a set of samples. d.Between each sample, even if the wavelength remains the same.
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Why is it necessary to run a blank before measuring the absorbance of a sample? To allow the lamp and electronics of the spectrophotometer to warm up before taking the sample absorbance reading. So that scattered light will be filtered before hitting the photodetector. To account for the absorbance caused by the cuvette and the solvent To account for the absorbance caused by the cuvette alone .
For the experimental data used in this lab, why was it okay to use the absorbance values instead of concentrations?
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1. Several procedures for the analysis of caffeine involve extracting the caffeine into an organic non-polar solvent (such as methylene chloride CH2Cl2). This about your experiment and what is discussed in the introduction. What might the advantage be for this approach? What is a disadvantage? 2. Think about what you said in the question above. If your sample was espresso, would your answer change? Why? 3. I was careless and ended up using a wavelength other than the peak (Say 250 nm). Would I still be able to carry out the experiment successfully? What might be the reason that I do not get optimum results? 4. I carried out the experiment using a scratched (or several scratches) cuvet for one standard, and clear cuvets for others. How might my calibration curve change (improve or get worse and why)? Pllllz answer these questions as soon as possible
Prepare a 1:200 dilution of the 20 mM Coomassie solution to measure the max wavelength—you need 2 ml for the absorbance measurement but the dilution does not matter as long as the absorbance is in the range of 0.2 to 0.6. Set the initial wavelength at 450 nm. Blank the spec with a tube containing 2 ml water. Use the 1000 ul pipette for water because you need to deliver the same amount of water in each tube for the next exercise. Why is it when the calculations are done for the given values above, the value for ml is 0.01 for coomassie blue?
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When do you need to blank a spectrophotometer (Spec 20)? After completing all data collection. After the wavelength is changed. Before running a set of samples. Between each sample, even if the wavelength remains the same.