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Experimental Design and Methods in Chemistry

Energy of a Single Photon

Proteins and DNA absorb light in the 282 nm range in the spectrophotometer. what is the frequency? Obtain the energy of a single photon of this wavelength?

Von Weimarn Ratio/Gravimetric Factors

3. What information, concerning optimum conditions of precipitation does the von Weimarn ratio give us? von Weimarn Ratio/Gravimetric Factors. See attached file for full problem description.

Percent of Manganese in the Sample

A 0.500-g sample is analyzed spectrophotometrically for manganese by dissolving it in acid and transferring to a 250-mL flask and diluting to volume. Three aliquosts are analyzed by transferring 50-mL portions with a pipet to 500-mL Erirnmeyer flasks and reacting with an oxidizing agent, potasium peroxydisulfate, to convert the

Analytical Chemistry Problem Set

35. You are required to prepare working standard solutions of 1.00 x 10^-5, 2.00 x 10^-5, 5.00 X 10^-5, and 1.00 x 10^-4 M glucose from a 0.100 M stock solution. You have available 100 mL volumetric flasks and pipets of 1.00-, 2.00-, 5.00-, and 10.00-mL volume. Outline a procedure for preparing the working standards. 38. A 0

Random or Systematic Error with a Pipet

Suppose that a 25-mL transfer pipet consistently delivers 25.031+/- 0.009mL when drained from the mark. Is this an example of random or systematic error? Comment.

Lowest-Energy Spectroscopic Terms

Show what electronic arrangements (electrons occupying sub shells of different ml and ms) that would lead to spectroscopic terms 6H, 5I and 8S, and identify one element each that have these terms as (see attached) the lowest energy spectroscopic terms. See attached for full formatting.

Interpretation of 1H NMR 4-vinylbenzoic Acid

I am doing a lab report and need to interpret the 4-vinylbenzoic acid 1H NMR spectrum above. 4-vinylbenzoic acid looks like this: I was given a help on brainmass: "4-Vinylbenzoic acid is an aromatic carboxyllic acid. there are three distinct groups in this molecule: benzene ring,vinyl group and -COOH group. In all there

1H NMR Spectrum Interpretation

I need to: provide an interpretation for all protons in the 1H NMR spectrum of 4-vinylbenzoic acid and indicate how the 1H NMR spectrum of the corresponding methyl ester would differ from that of the acid. On the 1H spectrum, I see a quartet around 6.8ppm which I don't know where it comes from, because I think it should be a

1H NMR Spectrum for 4-Phenylphenol

Refer to attached document. I have an 1H NMR spectrum of 4-phenylphenol (400 Mhz, CDCl3 solvent) and I have the spectrum assignment for the chemical shifts and corresponding protons. I would like an explanation of WHY each shift correspond with their particular protons. For instance, why are the protons adjacent to the pheno

Potassium Wave Motion

The potassium spectrum has an intense doublet with lines at 766.494 nm and 769.901 nm. Calculate the frequency difference between the 2 lines?

Spectrochemistry: Dilute the stock solution

Please help with the following problem. A spectrophotometric assay was to be carried out on a compound ε = 5000. The stock solution of standard had been made with a concentration of 0.0203M. Given a 1.000cm path length and a desired absorbance around 0.4-0.5, by what factor should the stock solution be diluted? (SHOW

Analytical Chemistry - Fluorometric method

(See attached file for full problem description) --- 23. In developing a fluorometric method, you measure a standard Analyte at 3.00 ppm (w/w) in the matrix at three different pH values: 2,5,8. You then compare the effects of internal calibration by adding 2.00ppm Analyte to your matrix vs external calibration via pure sta

Analytical Chemistry with Vitamin B

22. A company produces vitamin B tablets tha claim to provide 100mg of riboflavin. A bottle is drawn from the stock, and one pill is determined to contain 100.9 mg(= +/-1.1mg) of riboflavin. A)How many samples are needed to confirm with 95% confidence that the pills contain at least 100 mg of riboflavin. B) How should

Analytical Chemistry - aqueous solutions

17. A certain material "X" has an ether/water partition coefficient, KD = 3.3. If 55 mL of 12 ppt aqueous solution is extracted with 6.0 mL of ether, how much X is drawn into the ether layer? 18. The amount of mercury in a freshwater stream is determined by flowing 500 m3 of water through a charcoal filter canister. The ch

NMR: Resonance Frequencies

1. a) Calculate the resonance frequencies of the following nuclei, given the values for the nuclear magnetic moment and spin, at a field strength of 10 kG. B_N = 5.05 * 10^-24 ergG^-1. nucleus I u (in multiples of B_N) 11B 3/2 2.688 17O 5/2 1.893 50V 6

Use of spectrophotometry to determine Ka

This involves the use of the equation; pH = pKa + log (activity coefficent of anion) + log (D -Dha)/(Da- - D), from the equation it is neccesary to plot pH against log(D - Dha)/(Da- -D). This appears to be the straight line eqn which can be solved (y = mx + c) for the function pKa + log (activity coefficient of anion

The Oxidation of Alcohol by Dichromate Ion

1) I'm given a spectrophotometer. How can I determine the rate law? I can only use the spectrophotometer to determine %T. How can I get from %T to concentration? What strategy do I have to use? Can you provide me a step by step strategy about how to get "from %T to concentration" and how to get "from concentration to rate law"?

Restaurant - Boiling Stones

I have a question that I found in a text book, can anyone help me answer it? It seems to be safe. Some of you are concerned with the fact that the operator of a Vietnamese restaurant used some stones as "boiling chips" in the pots where they cook food. Please provide a paragraph with rationale to support your argument/conc

Lab Experiment: How do I dissolve dirt?

Purpose: To introduce the student to a real world application of concepts learned so for in Analytical Chemistry. Apparatus: To be determined. Introduction: In this experiment you will be given a beaker containing dirt. Dissolve .25 grams using any method/chemicals/devices possible. You are NOT allowed to use hydrofluoric

95% Confidence Level and Systematic Error

We are using the book Analytical Chemistry 7th edition by Skoog, West, Holler, and Crouch This question requires all equations to be written out. Thanks so much! To test the quality of work of a commercial laboratory, 15 replicate analyses of a purified benzoic acid (68.8% C, 4.953%H) sample were requested. The absolute

Gas Chromatogram

Please refer to the attachments provided. When I did the gas chromatogram, I made a careless mistake, by not labeling the printout(A-D); A-C the 3 distillation fractions and D the undistilled residue. On the 1st printout w/ 4 peaks, I know that the highest peak is A and on the printout w/ two peaks I think the peak on the rt

Can equilibrium be maintained

When distilling toluene and benzene under equilibrium conditions can equilibrium be maintained if a) pressure is changed and if b) pressure and temp are changed? Explain by phase rule