A solvent passes through a chromatography column in 3.87 min, but the solute requires 7.60 min. What is the retention factor, k? k = What fraction of the time does the solute spend in the mobile phase in the column? tfraction in mobile phase = The volume of the stationary phase is 0.133 times the volume of the mobile phase in the column (Vs = 0.133V). What is the distribution constant, Kp, for this system? Kp =

A solvent passes through a chromatography column in 3.87 min, but the solute requires 7.60 min. What is the retention factor, k? k = What fraction of the time does the solute spend in the mobile phase in the column? tfraction in mobile phase = The volume of the stationary phase is 0.133 times the volume of the mobile phase in the column (Vs = 0.133V). What is the distribution constant, Kp, for this system? Kp =

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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16) Which of the following(s) is/are correct? I- Selectivity factor is the amount of time a solute spends in the stationary phase relative to the time it spends in mobile phase II- The retention time for an analyte is the time interval between its injection onto a column and its appearance at the detector at the other end of the column. III- Distribution constant is the ratio of the total solute concentration in the stationary phase to that in the mobile phase. A) I, II and III B) Only II C) I and III D) II and III E) Only III for GC2
The distribution constant for X between n-hexane and water is 8.9. What volume of n-hexane is required to decrease the concentration of X to 1.00 x 10-4 M if 45.0 mL of 0.0500 MX is extracted with a. 25.0-mL portions? Volume = mL b. 10.0-mL portions? Volume = c. 2.0-mL portions? Volume = = mL mL
4.columns with one million theoretical plates operating by slip flow. The figure shows the gradient separation of two forms of fluorescently labeled bovine serum albumin separated on a)50 x 2.1 mm UHPLC column of 1.7 µm C4 silica particles and b)10 mm x 75µm colloidal crystal column of 470 nm C4 silica nanoparticles. What are the main differences in the chromatogram? What is the reason for the difference? Why does the colloidal crystal column have such a high number of theoretical plates (N)? How is the problem of high pressures with very small particles overcome?
The standard addition method is used to analyze a sample of a river water for mercury. Solution A is made by pipetting 5.00 mL of undiluted sample in to a 10 mL volumetric flask and filling to the mark with DI water. Solution B is made by pipetting 5.00 mL of undiluted sample and 3.00 mL of 15.0 ppb of Hg standard into same 10.0 mL volumetric flask and filling to the mark with DI. Solution A and B are analyzed using atomic absorption spectroscopy and give a percent transmittance values of 56 % and 33 % respectively (not blank corrected). A blank has a transmittance of 96%. What is the corrected absorbance of both solution A and B? O A. Solution A: 0.123 Solution B: 0.463 O B. Solution A: 0.463 Solution B: 0.234 O C. Solution A: 0.123 O D. Solution A: 0.234 Solution B: 0.234 Solution B: 0.463
7 How is the variation in sample composition in a powder random mix influenced by the proportion of active ingredient particles and by the total number of particles in the sample?
What is the minimum distribution constant that permits removal of 99% of a solute from 50.0 mL of water with two 25.0-mL extractions with toluene? five 10.0-mL extractions with toluene?
The standard addition method is used to analyze a sample of a river water for mercury. Solution A is made by pipetting 5.00 mL of undiluted sample in to a 10 mL volumetric flask and filling to the mark with DI water. Solution B is made by pipetting 5.00 mL of undiluted sample and 3.00 mL of 15.0 ppb of Hg standard into same 10.0 mL volumetric flask and filling to the mark with DI. Solution A and B are analyzed using atomic absorption spectroscopy and give a percent transmittance values of 56 % and 33 % respectively (not blank corrected). A blank has a transmittance of 96%. What is the corrected absorbance of both solution A and B? OA. Solution A: 0.123 Solution B: 0.463 O B. Solution A: 0.463 Solution B: 0.234 O C. Solution A: 0.123 Solution B: 0.234 O D. Solution A: 0.234 Solution B: 0.463
In a reverse-phase separation, a solute was found to have a retention time of 19.6 min, while an unretained peak had a retention time of 1.45 min when the mobile phase was 20/80 v/v% methanol/water. (b) Calculate the k’ for the solute. (c) Calculate the new k’ if the mobile phase is changed to 60/40 methanol/water assuming identical void volume. (d) Calculate a solvent composition that would bring k’ from initial value to a value of 1.20 using tetrahydrofuran/water mobile phase rather than 20/80 v/v % methanol/water.
What is the minimum distribution constant that permits removal of 99% of a solute from 50.0 mL of water with five 10.0-mL extractions with toluene?
1. A sample of an infusion was diluted 10 ml to 250 ml and then 10 ml to 200 ml. It was then analysed and was found to contain sodium at 0.789 mg/100 ml. Calculate the concentration of sodium in the original sample in %w/v. The sample was composed of a mixture of sodium lactate and sodium carbonate in equimolar amounts. Calculate the amount of sodium lactate and sodium carbonate in mg/10 ml of the sample (Na = 23, lactate = 89, carbonate = 60) 2. 0.641 g of a semi-synthetic alkaloid was dissolved in 25 ml of 1% w/v acetic acid and was analysed directly by HPLC. The solution was found to contain 1.42 mg/100 ml of an impurity. What is the level of impurity in % w/w and ppm? 3. Calculate the pH of a buffer system made by dissolving 1.2 g of acetic acid and 0.82 g of sodium acetate in 500 ml of distilled water (pKa of acetic acid = 4.7) 4. Convert the following concentrations into the required expression. Concentration given Expression required 0.5% NaCl molarity 1 mM of KBr…
Chromatography involves the separation of two or more compounds/ions caused by their molecular interactions with two phases. True False
The standard addition method is used to analyze a sample of a river water for mercury. Solution A is made by pipetting 5.00 mL of undiluted sample in to a 10 mL volumetric flask and filling to the mark with D water. Solution B is made by pipetting 5.00 mL of undiluted sample and 3.00 mL of 15.0 ppb of Hg standard into same 10.0 mL volumetric flask and filling to the mark with DI. Solution A and B are analyzed using atomic absorption spectroscopy and give a percent transmittance values of 56 % and 33 % respectively (not blank corrected). A blank has a transmittance of 96%. Which of the following technique can be used to determine the amount of mercury in the undiluted sample of river water? O A. IR spectroscopy O B. Cold vapor atomic absorption OC. Hydride generation atomic absorption OD. Electrothermal atomic absorption