5. By a fractional precipitation a polymer A with most probable distribution (I = 2.0) and an osmotic molecular weight of 120,000 is separated into two fractions B and C with molecular weights, 200,000 and 300,000, respectively, determined by light scattering. Calculate the weight of B that would be obtained from 100 g of initial polymer A. If both B and C have the same polydispersity, what is the value of the polydispersity index ?

5. By a fractional precipitation a polymer A with most probable distribution (I = 2.0) and an osmotic molecular weight of 120,000 is separated into two fractions B and C with molecular weights, 200,000 and 300,000, respectively, determined by light scattering. Calculate the weight of B that would be obtained from 100 g of initial polymer A. If both B and C have the same polydispersity, what is the value of the polydispersity index ?

Macroscale and Microscale Organic Experiments

7th Edition

ISBN:9781305577190

Author:Kenneth L. Williamson, Katherine M. Masters

Publisher:Kenneth L. Williamson, Katherine M. Masters

Chapter7: Extraction

Section: Chapter Questions

Problem 1Q

See similar textbooks

Similar questions

Hexanoic acid was added to an immiscible biphasic solvent system, water and CCl4 at 20.0OC and the equilibrium concentrations of hexanoic acid were determined to be 3.66 g/L in H2O and 67.0 g/L in CCl4. Caluclate the distrubution coeffiecent (D2) of hexanoic acid in water with respect to CCl4.
Hexanoic acid was added to an immiscible biphasic solvent sysem, water and CCl4 at 20.0OC and the equilibrium concentrations of hexanoic acid were determined to be 3.66 g/L in H2O and 67.0 g/L in CCl4. Caluclate the distrubution coeffiecent (D1) of hexanoic acid in CCl4 with respect to water.
(b) The distribution ratio for X between n-hexane and water is 8.9. Calculate the concentration of X remaining in the aqueous phase after 50.0 mL of 0.200 M X is treated by extraction with the following quantities of n-hexane? (i) one 40.0-mL portion; (ii) two 20.0-mL portions; (iii) four 10.0-mL portions. (iv) Comment on the results obtained from (b)(i) to (iii).
The distribution coefficient (K) of formic acid (HCO2H) in 1-octanol versus water is 0.39. If a solution of 4.00 grams of formic acid in 100.00 mL of 1-octanol is extracted with one 10.00 mL portion of water, how many grams (to the hundredths place) will remain in the organic layer?
Propose how the components of a mixture containing Toluene (b.pt= 110.50C) and CCl4 (b.pt. =770C) can be separated. Include how can you justify the effective separation of the components.
A mixture of n-heptane, tetrahydrofurane, 2-butanone, and n- 1 propanol elutes in this order when using a polar stationary phase such a Carbowax. The elution order is exactly the opposite when using a nonpolar stationary phase such as polydimethylsiloxane. Explain the order of elution in each case. 2 The molar solubility of pbBr2 is 0.01M. Calculate ksp for pbBr2. The cell (Ag/AGCI ref // SO4-2, PbSO4(s)/Pb) was found to have a potential of -0.561V. Calculate the concentration of SO4-2 in the cell given: PbSO4(s) + 2e- O Pbis) + SO4-2 E= -0.350v 3. Note: E A/AgCi ref = 0.1970v Why it's not necessary to use Quartz cuvette in this experiment? 4 1-Write the full words for the following acronyms: • VR: • ISC: •EC: What is the difference between the excitation and emission spectrum?
A student performs a crystallization on an impure sample of biphenyl. The sample weighs 0.5 g and contains about 5% impurity. Based on his knowledge of solubility, the student decides to use benzene as the solvent. After crystallization, the crystals are dried and the nal weight is found to be 0.02 g. Assume that all steps in the crystallization are performed correctly, there are no spills, and the student lost very little solid on any glassware or in any of the transfers. Why is the recovery so low?
Describe in words and by means of complete chemical equations, how a mixture of 1.25 g of benzoic acid tertbutylbenzene can be separated by applying the separation of 2 components by liquid-liquid extraction.
Q1. (a) In each of the following cases (I. to III.) identify which polymer in each pair has the greatest Tg and then explain your selection in terms of molecular structures. Assume that molecular weight differences are insignificant. Note: PMV = pendant molar volume/ cm³/mol Pair I Section A Answer ALL questions in this Section Pair II Pair III Polymer 1 H₂ +²2² 0+. Repeat unit A ht Polymer 3 (PMV=92.3) 3 Polymer 5 (PMV-60.1) tyt OC-CH₂ Polymer 2 | to-0²-0-0 H₂ + -ot Polymer 4 (143.9) (b) Consider the following repeat units A and B, state which polymer is likely to be amorphous and which is likely to be semi-crystalline then explain why in terms of the structure of the repeating units. to *** Polymer 6 (PMV=70.3) Repeat unit B t
Calculate the amount of ester, CH3COOCHs formed when 2.00 moles of ethanoic acid,CH3COOH and 2.00 moles of ethanol, C2HsOH are allowed to come to equilibrium at 300 K CH3CO0C2Hs(aq) + H2O(1) Kc=4.12 (ANS = nCH3COOCHs= 1.414 mole; mass CH3COOC2Hs= 124.43 g)
Two different proteins X and Y are dissolved in aqueous solution at 37 ∘C. The proteins bind in a 1:1 ratio to form XY. A solution that is initially 1.00 mM in each protein is allowed to reach equilibrium. At equilibrium, 0.17 mM of free X and 0.17 mM of free Y remain. What is Kc for the reaction? Express your answer using two significant figures.
(b) The distribution ratio for X between n-hexane and water is 8.9. Calculate the concentration of X remaining in the aqueous phase after 50.0 mL of 0.200 M X is treated by extraction with the following quantities of n-hexane?