Multiple choice questions. Ci the letter of best answer to each query (o pts. 1)
ID: 494510 • Letter: M
Question
Multiple choice questions. Ci the letter of best answer to each query (o pts. 1) The primary reason for adding anhydrous sodium sulfate to an organic solvent used in an extraction from water is: a) Removal of residual sodium chloride b) Removal of residual water c) Neutralization of excess acid d) Neutralization of excess base 2) Acetone is considered to be a polar molecule because a) There is a large dipole moment associated with the c o bond b) There is a small dipole moment associated with the c obond c) There are very large dipole moments associated with the C-H bonds d) None of the above 3) In the bromination of cinnamic acid, why was cyclohexene added at the end of the reaction? a) To cool the reaction mixture bo To increase the reaction yield c) To remove excess bromine d) To catalyze the reaction iazonium salt? ine to a di a) NaNO, HCL cold b) Kmnoa, HCL, cold c) Ethyl ether, heat d NaNO, HCl, coldExplanation / Answer
1. The primary reason for adding anhydrous sodium sulfate to an organic solvent used in an extraction from water is
(b) removal of excess water
2. Acetone is considered to be a polar molecule because
(b) There is a small dipole moment associated with the C=O bond
3.
4. The chemicals and reaction condition needed to convert 4-nitroaniline to a diazonium salt is
(d) NaNO2, HCl and cold (diazotization reaction)
5. The increasing order of polarity among biphenyl, benzoic acid and benzyl alcohol is given below:
biphenyl < benzyl alcohol < benzoic acid. Thus in a TLC plate if the mixture containing biphenyl, benzyl alcohol and benzoic acid is taken and hexane/ethylacetate solvent mixture is taken, the relative Rf values follows the order: benzoic acid < benzyl alcohol < biphenyl.
6. Rf value of compound A = Distance travelled by A/ Distance travelled by hexane solvent
Rf value of compound B = Distance travelled by B/ Distance travelled by hexane solvent
Rf value of compound C = Distance travelled by C/ Distance travelled by hexane solvent
Compound A is the most polar compound among A, B and C.
Since B is least polar and A is the most polar, upon chaning solvent from hexane to acetone on TLC plate, Rf value of B will be least affected while that of A will be significantly affected due to intercation with the solvent. Rf value of A, B and C will increase. however, increase in case of A will be maximum.
Since alumina plate is basic in nature, upon eluting in case of A (which is basic in nature), we will have maximum Rf value.
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