A kinetic experiment is carried out in a flow tube where the flow rate is 25 m s¹. The detector is a spectrophotometer, and absorbances are measured at various distances along the tube. The reactant has a molar absorption coefficient of 1180 mol-¹ dm³ cm¹ at 420 nm. The absorbances are measured using a 1 cm optical cell. Use this information, and that in the following table, to calculate [reactant] as a function of time. Then plot a graph of [reactant] versus time and comment on its shape. May plot using excel. distance cm A 2.0 0.575 0.457 4.0 8.0 0.346 0.232 6.0 10.0 0.114

A kinetic experiment is carried out in a flow tube where the flow rate is 25 m s¹. The detector is a spectrophotometer, and absorbances are measured at various distances along the tube. The reactant has a molar absorption coefficient of 1180 mol-¹ dm³ cm¹ at 420 nm. The absorbances are measured using a 1 cm optical cell. Use this information, and that in the following table, to calculate [reactant] as a function of time. Then plot a graph of [reactant] versus time and comment on its shape. May plot using excel. distance cm A 2.0 0.575 0.457 4.0 8.0 0.346 0.232 6.0 10.0 0.114

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter17: Applications Of Infrared Spectrometry

Section: Chapter Questions

Problem 17.9QAP

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Given the following data find the Molar absorption coefficient for Fe(SCN)^2+}Fe(SCN)X2+, (M−1 cm−1), if the length is 2.24cm. FIND THE UNROUNDED VALUE. Unrounded Rounded Molar absorption coefficient for \ce{Fe(SCN)^2+}Fe(SCN)X2+, (M−1 cm−1) Sample FROM PRELAB EXPERIMENTAL DATA CALCULATED VALUES 0.000300 M Absorbance Fe(SCN)X2+]equ, (M) --> for next bar 1 1.50 0.210166 0.0000300 2 3.50 0.466178 0.0000700 3 7.00 0.912604 0.000140 4 10.00 1.348948 0.000200 SLOPE, (M−1) INTERCEPT R^2R2 Unrounded 6.66606 × 103 1.20727 × 10-3 0.998979
A student prepared several solutions of an unknown molecule, each at a different concentration. The absorbance of each solution was measured at 630 nm with a path length of 0.760 cm. The student then plotted the absorbance of each sample vs. its concentration (in uM), and found a best-fit line of y = 0.00626x + 0.00732. Calculate the molar absorptivity of the unknown molecule (in M-1 cm-1).
An analysis of Zn2+ in food sample by atomic absorption spectroscopy gave a calibration curve of A = 456.8 CZn + 1.234 where A is the absorbance. The concentration of Zn2+ (CZn) is expressed in molarity. If a measurement of the blank gave a signal of 1.234 ± 0.050 (mean ± S.D. ). What was the limit of detection for Zn2+ in molarity?
An absorbance calibration curve for Zn was fitted to equation A = 0.913×`Zn, ppm`. Flask 1: To the first flask, a 1.00 mL aliquot of the unknown Zn solution was diluted to 100.0 mL in a volumetric flask; the absorption intensity from this sample was measured to be A = 0.204. Flask 2: To a second flask, a 1.00 mL aliquot of the unknown Zn sample and a 1.00 mL aliquot of 10.00 ppm Zn solution were added and diluted to 100.0 mL in a volumetric flask; the absorbance of this sample was measured to be A = 0.294. Calculate the % spike recovery for the analysis and report to the nearest whole number. Hint: A=mC of the type y=mx, so C=A/m %Spike=100%((Cspike-Coriginal)/Cadded)) Cadded can be found from C1 V1=Cadded V2.
The data given below was generated by a student in Bio 240L during a Bradford Assay. A standard curve was generated by preparing a set of standard samples of protein (bovine serum albumin) and adding the dye Coomassie Brilliant Blue, When the protein binds to Coomassie Brilliant Blue it absorbed light at 595 nm with an extinction coefficient of 43,000 M-1 cm-1. After the dye binding reaction was complete, absorbance values for each protein standard solution were measured at 595 nm and recorded. Standard # 1 2 13 4 Concentration of protein binded to Coomassie Brilliant Blue (M) 6.35x10-7 1.23x10-6 3.85x10-6 5.68x10-6 OOO Absorbance at 595 nm 0.093 0.176 0.560 0.813 Prepare a standard curve with the student generated data. What is the slope from the standard curve rounded to four sig figs and no units? 1.4 143398 6.972x10-6 1.434x105
If the measured absorbance at 280 nm of the protein in a 1.00-cm cuvette = 0.564, what is the extinction coefficient at this wavelength?
Chemistry Atomic absorption analysis of Zn gave a calibration best fit line of A=0.670(ppm Zn) The detection limit was determined for this analysis using a 0.020 ppm Zn solution. The standard deviation of the absorbances for 11 samples of the solution was found to be 1.560 x 10-3 and the slope of the calibration curve was 0.026. Calculate the detection limit, Cq, (in units of ppm) for this instrument. Give your answer to 3 places after the decimal place.
A solution containing two different fluorescent compounds, Ben and Jerry, were analyzed for their individual concentrations in the mixture. Standards of pure Ben and pure Jerry were prepared at a concentration of 500.0 mM and were run in a UV-Vis Spectrophotometer to determine their absorption properties. Absorbance Wavelength Compound Ben 500 mM Compound Jerry 500 mM 400 nm 0.137 0.136 450 nm 0.312 0.113 500 nm 0.154 0.078 550 nm 0.076 0.079 600 nm 0.227 0.148 650 nm 0.230 0.230 700 nm 0.151 0.357 750 nm 0.157 0.246 800 nm 0.154 0.154 A standard curve of the standards was also prepared to help determine the concentration of each component in the solution. The solution produced an absorbance reading of 0.486 at the Amax of Ben, and 0.463 at the Amax of Jerry. STD CURVE BEN Amax Ben Amax Jerry STD CURVE JERRY Amax Ben Amax Jerry CONC (mM) ABS ABS CONC (mM) ABS ABS 100 0.074 0.025 100 0.037 0.074 200 0.148 0.057 200 0.081 0.148 400 0.284 0.103 400 0.164 0.284 800 0.607 0.218 800 0.287…
A student prepared several solutions of Molecule Bright, each at a different concentration. The absorbance of each solution was measured at 405 nm with a path length of 0.730 cm. The student then plotted the absorbance of each sample vs. its concentration (in mM), and found a best-fit line of y = 3.726x + 0.828. Calculate the molar absorptivity of the Molecule Bright (in M-1 cm-1).
State True/False for the following statements. 1. In UV-Vis spectrophotometric analysis, the 2.82% transmittance of solution has an absorbance value of 1.55. 2. Peaks resulting transitions from n→ are shifted to shorter wavelengths (blue shift) with an increasing of solvent polarity. 3. In molecular absorption spectrophotometry, the relationship between transmittance and concentration is not linear while the absorbance vs concentration is linear. 4. Beer's Law states that absorbance of a compound is directly proportional to the log of the concentration of the absorbing species. 5. Different colors of the lights are refer to the waves with different amplitudes.
Fe2+ is used as a catalyst for the oxidation of luminal by H,02. The resulting chemiluminescence increases linearly with Fe2* concentration. Exactly 1.0 mL of water was added to a 5.0-mL sample of an unknown Fe2* solution, followed by 2.0 mL of H20, and 1.0 mL of luminol. The chemiluminescence intensity was found to be 16.1. When 1.0 mL of 4.75 x 10 SM Fe2+ solution was added to another 5.0-mL of the unknown Fe2+ solution, followed by 2.0 mL of H,0, and 1.0 mL of luminol, the chemiluminescence intensity was 39.6. Calculate the concentration of iron ions in the sample. O 6.5 x 106 M 9.0 x 10 5 M 1.4 x 10 5 M 1.3 x 104 M 1.6 x 104 M
The levels of Vitamin B1 in a sample of milk was determined using the Standard Addition method and technique of fluorescence spectroscopy. 18.0 ml of the milk sample was diluted to 20.0 ml using distilled water and then the fluorescence was measured. The resulting signal was 210 units. A spike was made by taking 18.0 ml of the same milk sample, adding 1.0 ml of a 6.0 ppm Vitamin B1 standard solution, and then diluting to 20.0 ml using distilled water. The signal of the spiked milk was 540 units. Calculate the concentration of Vitamin B1 in the original milk sample (in ppm). Report to 3 decimal places.