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Three students did a chromatography experiment, where Rf = distance of solute / distance of solvent. What could be the possible errors why student 3 had results that are quite far from that of students A and B?

A student runs a TLC of a sample using a nonpolar development solvent. The TLC shows one spot. The MP of the same sample is 115.5 - 118.2 oC. What can we conclude from the experimental results. Group of answer choices The incorrect development solvent was used. The sample is pure. The sample is non polar. The sample is polar.

Question:  Using a sample of aspirin for HPLC analysis. If the aspirin was contaminated (wet) with trace amounts of a solvent such as ethyl acetate, hexane, or water, would this contaminant be detected and appear as a peak in the HPLC chromatogram? Briefly explain based on the type of detector used in HPLC analysis and what type of compounds can be detected. My Answer: The HPLC analysis detects chromophores, compounds with multiple double bonds. Since water, ethyl acetate, and hexane all lack multiple pi bonds this will not be detected in the HPLC.  -Question for you, is this complete (and correct), and should I include anything about UV detection? Is UV detection used in HPLC? I thought it was only used on TLC to show compunds that arent visable.

PART ONE: Preparation of FECNS* Solution Prepare the two solutions in table 1 by accurately measuring the required volumes of distilled water and CNS into two labeled test tubes. The absorbance of the solutions must be measured soon after adding the Fe" solution from a buret. TABLE 1 Fe 5 ml 5S mL Solution Distilled Water CNS 2 mL Total Volume 3 ml 2 ml 10 ml 3 mL 10 ml In this part of the experiment you are to explore what the above quote means. As a PRELIMINARY Exercise, formulate a hypothesis as to what would happen under each of the following circumstances: 1. 1ml of 0.0020 M CNS' solution is added to the unused portion of solution 1 in the test tube 2. One drop of 0.20 M CNS solution is added to the unused portion of solution 2 in the test tube.

20,18,2,4,15,15,10 Using these data, construct a 80% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal.  Construct the 80% confidence interval. Round your answer to one decimal place.

Use the calibration curve or linear regression equation to determine the concentration of FD&C blue dye No. 1 in Kool-aid. Food Coloring is 0.026 M in FD&C blue dye No. 1 7.5 x 10 -5 M is 29 mL -> 1000 mL

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Determine the correct answer for the following.question: A quality control (QC) sample was run in replicates of six to produce the following concentrations values: 12.2, 11.6, 11.9, 12.3, 12.8, and 11.7 ug/L. Is this level of analytical method precision acceptable for this group of QC replicates? O 3.3%, YES O 3.3%, NO O 5.5%, YES O 5.5% NO Question 9 Determine the correct answer for the following question: One definition of analytical method accuracy in a GLP laboratory is +20 percent relative error (RE) of the measured mean sample concentration to that of the true concentration such that %re = [(Measured Mean Concentration - True Concentration)/True Concentration] x 100 A single quality control (QC) sample was prepared at a concentration of 12.5 ug/Land run in replicates of six to produce the following concentrations values: 12.5, 11.9, 14.2, 12.2, 13.7, and 14.1 ug/L. Is this level of analytical method accuracy acceptable for this QC sample?

how to get uncertainty?

NaOH is the base (please elaborate) Thank you!

From a 10-mL sample, a 1-mL aliquot was taken and diluted to 100mL. From this, a 5-mL aliquot was taken and diluted to 20mL.The final 20mL was found to have a concentration of 0.004M analyte X.What is the concentration of analyte X in the 10-mL sample?

please answer a,b,c,d

Color BEFORE adding Color AFTER adding Intensity of color AFTER adding FeCl3 Test Tube # FeCl3 FeCl3 #1 (salicylic acid) clear lilac 100% #2 (commercial aspirin A) clear slightly pink 50% #3 (commercial aspirin B) clear lilac 95% #4 (aspirin from your clear pink 20% synthesis above) #5 (control) clear clear 0% Based on this data and the melting point of Aspirin, how pure is the synthesized product?

1. The concentration of NaOH from the best three of your trials. 2. The average concentration of 3 of your trials (only use 3 trials) 3. The standard deviation of your 3 trials [If you have a calculator with stats on it, you can use that/bring it to class, but for the lab report you will have to write out your calculations.] 4. Your PPT.

Based on the first set of numbers, please help solve the rest.

line of best fit. y=0.001x + 0.1987, absorbance is 1.29. Calculate the concentration of your sample. units must be ug/mL

Complete the table and provide the percent (%) recovery for each extraction.

Look up the boiling point for each of the following compounds then determine the order that they will elute from the column. Use this elution order to identify the compound in each of the 6 standard chromatograms. Once you have identified the compound in each chromatogram, record its retention time. Compound Structure Compound Name Elution Order (1-6) Non polar → Polar Boiling Retention Time (From Chromatograms) Point Propyl acetate H H. H. Butyl acetate H. H. H H. H H. H. H. Methanol H O- Ethanol 2-butanone H H H. H. 4-methyl-2- pentanone H. H. HH H.

A new dye (DYE C) was developed and was analyzed against other dyes using paper chromatography. A solution 1:1 ethyl acetate: hexane was used as the eluent. The resulting chromatogram is shown at the photo. Determine the retention factor (Rf) values of each spot on dye C and what are the other dye/s present in dye C.

Analysis of Percent Organic Matter of * a soil sample was conducted and the data are shown below. Calculate the Percent Organic Matter of the sample. (Write answer with 3 significant figures with no %unit) Deionized water blank Reagent blank Sample with reagent Absorbance 0.001 0.089 1.231 Standard Solution (%) Absorbance 10 20 40 80 100 0.291 0.489 0.889 1.692 2.075

Spot in R lane Spot in Y lane Upper spot in U lane Distance traveled by spot (cm) Lower spot in U lane 3.00 Spot in B 5.00 lane 1.20 4.70 2.90 Solvent Rf front (cm) 5.90 5.90 5.90 5.90 5.90 Based on your TLC, which best describes the identity of the unknown food dye?

A student developed a new dye called Dye C. It was analyzed against other dyes using paper chromatography. A solution of 1:1 ethyl acetate:hexane was used as the eluent. The resulting chromatogram is shown in the figure.  Determine the retention factor (Rf) values of each spot on dye C. (use 2 decimal places)  What other dye/s are present in dye C and what is the dye with least number of pigments?

please answer b

This was a fractional distillation lab separating cyclohexane and toluene. I know A in the NMR analysis is the aromatic component of toluene but I am having a hard time figuring out the other two peaks. Which one represents the methyl group of toluene and what is the other peak (it might be water or some other impurity)?

The following data were obtained from a Bradford assay to determine the protein content in a sample: Protein content (μg) Absorbance value 0 0.000 2 0.022 5 0.065 10 0.106 20 0.178 30 0.299 40 0.380 50 0.472 unknown  0.150 a. use excel, another program, or graph paper to produce a calibration curve based on the data. b. Use linear regression (best fit line) to obtain the slope of the line c. Determine the unknown protein content for a sample that shows an absorbance reading of 0.150.

To quantify the amount of ethanol in a beverage, a technician prepared the first solution which contained 4.90 grams unknown, 1.00 grams acetonitrile, and 4.10 grams water. After the GC analysis which reported the peak areas of 5,742 for ethanol and 3,829 for acetonitrile, the technician added 0.20 grams ethanol to the first solution and ran the GC analysis again. This time, the peak areas of 6,382 for ethanol and 3,709 for acetonitrile for solution 2 were obtained. What was the percent by mass ethanol in the original beverage?

Sheet 5 From the following data determine the following: Define outlier and then identify the outlier in the data. Determine if the outlier should be kept of discarded from the data. Trial 1 2 3 4 HCl (mL) 22.3 28.4 29.8 29.3 NaOH (mL) 35.2 35.1 34.9 35.0

Just need a second pair of eyes to confirm whether or not my solution is correct. Thanks

A student performed a chromatography experiment to determine the Rf value of an unknown amino acid. The distances traveled by the amino acid and the solvent line were 3.0 cm and 8.5 cm, respectively. What is the Rf value for this amino acid? 0.3 cm O 0.35 1.8 5.5 0.85 cm 0.65 O 2.8

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A student weighed out 0.150 g of protein powder and dissolved it in 100 mL of water (Solution 1). The student then diluted this solution by transferring 1 mL into a 25 mL flask and diluting with water (Solution 2). Finally, 1 mL of that solution was transferred to a test tube and combined with 4 mL Bradford reagent. The absorbance of the solution in the test tube was 0.144. Assuming that the best fit linear line of the standard curve was y=0.04144x+0.01521 (μgmL), calculate the percent protein by mass in the original protein powder.

Which is correct?     Random errors affect accuracy and systematic errors affect precision.     An accurate result shows agreement with the true or accepted value.     Precise results can contain significant random error, but little systematic error.     The standard deviation is a good measure of accuracy.   Polydimethylsiloxane (PDMS) stationary phases have low polarities.  Which of the following statements is TRUE about gas chromatography using PDMS stationary phases?     The gas chromatography column is typically packed with silica microparticles.     An oven is used to control the column temperature because a constant temperature is always needed in gas chromatography     Octane (C8H18, boiling point: 126 ºC) is eluted later than dodecane (C12H26, boiling point: 216 ºC)     3-Pentanone ((C2H5)2CO, boiling point: 102 ºC) is eluted later than propanol (CH3CH2CH2OH, boiling point: 97 ºC)