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# Experimental Design and Methods in Chemistry

### Graphing solubility - A student decided to measure the amount of salt that would dissolve in 50 ml of water at different temperatures ...

A student decided to measure the amount of salt that would dissolve in 50 ml of water at different temperatures. The student found that the solubility at 10 degrees centigrade (10° C), was .56 grams of salt. At 40° C, 2.35 grams dissolved and the solubility at 70° C was 3.85 grams of salt. Create a "Best fit" graph for th

### Candle Lab

Experiment Observations Results and Explanations A. Reigniting a Candle B. Water Suck Up C. Extinguishing a Candle with Aluminum Foil D. Candle Condensation E. Extinguishing a Candle with Carbon Dioxide 1. Why would the candle reignite with a match held away from the wick? 2. a) Explain how the candle would

### NMR Spectroscopy - Solve the structure of unknown A

Hi, I have some data to help me solve a structure via High Resolution NMR, however being new to this, I am having extreme difficulty, and was wondering if someone could help please - or even point me in the right direction as how to go about solving for structure A? A has a molecular formula: C12H15O4N. The 13CNMR data sh

### Infrared spectroscopy

On this site http://www.chemguide.co.uk/analysis/ir/interpret.html#top it shows an infra red spectrum of ethanoic acid and shows a very broad trough between 2500 - 3300 cm ^-1 taking this from the point where the line graph starts to drop it looks more like 2800 - 3800 cm ^-1 do you have to take these measurements from

### Statistical Method (Concentration and Absorbance)

1. A gun shot residue containing barium and lead is analysed using atomic absorption. Residue from sample collected in Glasgow and Inverurie are also available Glasgow gun shot residue (n-20) Ba (o.12+/-0,005%), Pb (5.2+/-2.0%) Inverurir (n=5) Ba (0.22+/-0,001%), Pb (7.2+/- 1.0%) (a) Describe the necessary parts of an

### Modern Analytical Techniques

Write an account on what you consider to be the most significant advances made in the field of modern analytical techniques during the last five years. Include specific examples in your answer.

### Types of Stationary Phases used for Chiral Separations in HPLC

Describe the types of stationary phases used for chiral separations in HPLC including structural requirements.

### Beer's Law for Concentration

1. Calculate the concentration of each calibration standard. 2.Plot the data on the attached graph paper. 3. Calculate the slope. What is the average slope? What are the units? 4.Determine concentration of the diluted unknown. 5. determine the undiluted concentration of the unknown. The stock solution is 0.027 M KMnO4

### 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

### 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

### 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 &#949; = 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

### Calculate the number of grams of citric acid, C6H8O7, needed to make 2500mL of 0.4 M C6H8O7

1. Calculate the number of grams of citric acid, C6H8O7, needed to make 2500mL of 0.4 M C6H8O7. 2. How many grams of sodium hydroxide, NaOH, would you have to dissolve in 250 mL of water to make a 0.5 M solution of NaOH? 3. How many liters of water are required to make a 0.2M solution sulfide, Na2S, using 200g of Na2S?

### Miniature Laboratory Volcano Empirical Formula

63. A miniature laboratory volcano can be made with ammonium dichromate. When ignited it decomposes in a fiery display. (NH4)2Cr2O7(s) N2(g) +4 H2O(g) + Cr2O3(s). If 5.0g of ammonium dichromate are used and if the gases from this reaction are trapped in a 2.0 L flask at 25oC, what is the total pressure of the gas in the flask?

### Spectroscopic method to distinguish between isomeric acids

What spectroscopic method would you use to unambiguously distinguish between the following isomeric acids? Give an explanation of how the spectra are interpreted to give you an assignment for each compound. (a) CH3(CH2)3CO2H (b) (CH3)2CHCH2CO2H (c) (CH3)3CCO2H

### 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

### Identifying Carbohydrates

An unknown carbohydrate could be reduced by a series of steps to a compound with five carbons. It does give a positive Benedicts test and it has two chiral carbons. What is the structure consistent with these facts?

### Absorption Spectrum

The 12C16O absorbs in the infrared region of the spectrum at 2145 cm^-1. Calculate the position of the absorption of 13C16O.

### NMR: Resonance Frequencies

See the attached file for the problem. 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

### Basic principles of qualitative analysis - Inorganic Chemistry, analytical chemistry

Assumed we get any sample to find out its compounds or chemical elements. Our first step shouldn't be to switch on the "state of the art" analysis equipment. We should start to solve the basic questions. These information will help us later to specify the final methods. Main attention is payed to the following points: * source

### 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