Lab 5 -Electrocardiography_FA20 Version

Sample #1 has an absorbance of 0.300. Sample #2 is the same substance and has an absorbance of 0.600 using the same equipment. What is the relative concentration of the second sample? Select one: a. The concentration of sample #2 is the square root of that of #1. b. The concentration of sample #2 is that of sample #1 squared. c. The concentration of sample #2 is half that of sample #1. d. The concentration of sample #2 is twice that of sample #1.

NAME PRELAB QUESTIONS These questions should be answered before coming to lab, and included when you turn in your lab outline and data sheets. 1. The dissolved compound in a sample has an absorbance value of 0.250. How would you expect the absorbance to change if: a. The concentration of the dissolved compound is tripled? b. The concentration of the dissolved compound is halved? 2. If you have a solution of unknown concentration, describe how you could determine the approximate concentration. 0.S a.r 0.1 6.0 0.0

At the end of the experiment you will be assessing the purity of your aspirin by measuring its absorbance at 525nm. If the absorbance measurement is found to be 0.040 then what is the % salicylic acid impurity in your aspirin? a. 0.06 b. 0.25 c. 0.15 d. 0.44 e. 0.35

Which statement about luminescence is FALSE? Select one: O a. Luminescence is emission of light from an excited state of a molecule. O b. At low concentration, emission intensity is proportional to analyte concentration. c. Emission comes at higher energy (shorter wavelengths) than absorption. d. Luminescence is quenched by self-absorption at high analyte concentrations. e. Luminescence is inherently more sensitive than absorption.

Answer last 3

Using the graph below, what does the R2 value tell us about the data?    A.The data is precise but inaccurate.    B.The data fits the curve well.    C.The data is precise.    D.The data is accurate.     E.The data is precise and accurate.

3. Using the data at right: a. Calculate the absorbance of each sample. You will need to express the %T values as decimals before calculating the logarithms. (e.g., for T = 25%, A = -log 0.25 = 0.602) b. Use the graph paper on the back of this page (or a spreadsheet) to plot absorbance vs. concentration. Make a proper graph, with labeled axes, uniform scales, etc. Use a ruler to draw the best-fit line.. C. Use the graph to find the concentration of the un- known sample. (Draw dotted lines on the graph showing how you found your answer.) CONCENTRATION PERCENT (ppm) TRANSMISSION 0 100.0 100 74.1 200 54.9 300 40.7 400 30.1 500 22.3 unknown 31.6 ABSORBANCE

Answer 4

750 400 11. Short answer. Refer to the color wheel on the right. If a solution is illuminated with white light and absorbs all wavelengths between 480 and 560 nm, what color would it appear to be? Violet Red 430 630 Blue Orange 480 590 Green Yellow 560 12. Short answer. You will need the color wheel on the right. Look at the absorption spectrum of the solution shown on the right. What color would this solution be? 800 13. Short answer. Look at the image of a spectrophotometer on the right. Structures/knobs A-E are labeled. Which knob will you have to use to zero the instrument itself? 20D BIOLOG. 14. Short answer. According to Beer's Law, given that Molar Absorptivity and path length is usually constant, Absorbance A is directly proportional to 15. Choose the one answer that fits best. Which of these is not standard components of a spectrophotometer? a. A sample chamber to hold your tube with sample solution b. A light source c. A prism or grating to filter out certain wavelengths of…

Determine the standard concentration of A through E and then the absorbance. I just need clarification on if I add together the two ml values given.

Question 3: UV Spectroscopy (Beer's Law) The molar absorptivity of an organic compound is 15,000 M-¹cm-¹ a. b. What concentration of this compound would give an absorbance of 0.75? (Assume a light path of 1.0 cm and calculate the concentration in moles per liter.) How would the absorbance change if the light path was changed to 2.0 cm?

Why were the absorbance measurements recorded at lambda max (504 nm)?   Question 1 options:   at lambda max impurities in the sample do not absorb any light   Because the allura red dye absorbs red color at 504 nm   at lambda max the absorbance is the most sensitive to dye concentration   at lambda max the absorbance is the least sensitive to dye concentration

Question 11 Which of the indicated protons would have the smallest pKa value? C. H. a. CH3 .C. CC-H C H- H. d. b. a by O d

2. Add the absorbance of your Part III solution to the graph. Llse the of best fit of your qraph to calcuate its line concentration. Concentraton vs Absorbance 1.6 con c: 0.003M 1.4 1.2 0.8 0.6 0.4 0.2 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 Concentration Co.003M) Concentration you have calculated in 2 is CCrO, of Ag CrO4. calculate your experimental ksp of Ag CrO4. = [Cr O4]? Use it to 2. %3D ksp of AgCr Oy = CAg+] [CrO4] Absorbance te Out

The concentration and absorbance data below were collected for compound X. A sample of compound X of unknown concentration has a corrected average absorbance of 0.5621 (3 replicate measurements). Calculate the y-intercept. CONCENTRATION (mg/mL) ABSORBANCE 5 0.422 10 0.510 15 0.621 a. 0.299 b. 0.222 c. 0.319 d. 0.553

Please answer all and post below the answer the source from where you got the answer thank you!

What is a characteristic feature of halogens on the mass spectrometry spectra? A. They have abundant isotopic peaks B. They have m/z values less than 100 C. They do not show up on mass spectrometry D. They possess at least 10 peaks with equal intensity

what is the reading of this buret?

What is the arrow pushing pattern labelled "1"? 1 -Br H H Br 2. 4. :Br: 3.