Question 1

The one aldehyde and the one ketone with a molecular formula of C3H6O are stereoisomers

Accepted Answer

false

Question 2

Aldehydes and ketones both contain a carboxyl group

Accepted Answer

false

Question 3

The VSEPR model predicts bond angles of 180Â° about the carbonyl carbon of aldehydes and ketones

Accepted Answer

false

Question 4

The carbonyl carbon of a ketone is not a stereocenter.

Accepted Answer

true

Question 5

The one aldehyde and the one ketone with a molecular formula of C3H6O are constitutional isomers

Accepted Answer

true

Question 6

Aldehydes and ketones both contain a carboxyl group.

Accepted Answer

false

Question 7

The VSEPR model predicts bond angles of 120Â° about the carbonyl carbon of aldehydes and ketones.

Accepted Answer

true

Question 8

The carbonyl carbon of a ketone is a stereocenter

Accepted Answer

false

Question 9

Aldehydes, Ketones and Carboxylic acids

Accepted Answer

contain carbonyl groups, They are highly polar molecules.They boil at higher temperatures.Lower members are soluble in water because they can form H-bond  with water.  Higher members are insoluble in water due to large size of their  hydrophobic group.

Question 10

ethers

Accepted Answer

hydrocarbons and weakly polar compounds

Question 11

Aldehydes are prepared by

Accepted Answer

a.Dehydrogenation of primary alcohols  b. Controlled oxidation of primary alcohols.  c. Controlled and selective reduction of acyl halides  Aromatic aldehydes can be prepared bya.  Oxidation of toluene with chromyl chloride or CrO3 in the presence  of acetic anhydride  b. Formylation of arenes with carbon monoxide and Hydrochloric acid  in the  presence of anhydrous aluminiumchloride / Cuprous chloride  c. Hydrolysis of benzal chloride

Question 12

Ketones are prepared by

Accepted Answer

bya.  oxidation of secondary alcohols  b. Hydration of alkenes  c. Reaction acyl chlorides with dialkylcadmium  d. By friedel crafts reaction  Carboxylic acids are prepared by -  a. oxidation of primary alcohols, aldehydes and alkenes  b. hydrolysis of nitriles  c. Treatment of grignard reagent with carbondioxide.

Question 13

CARBOXYLIC ACID

Accepted Answer

Carboxylic acids having an ? - hydrogen are halogenated at the ? -position on  treatment with chlorine or bromine in the presence of small amount of red  phosphorus to give ? -halocarboxylic acids.

Question 14

ESTERIFICATION

Accepted Answer

Carboxylic acids react with alcohols or phenols in the presence of a mineral acid  such as conc.H2SO4 as catalyst to form esters.

Question 15

Aldehyde

Accepted Answer

Many fragrances are aldehydes. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group, which is any generic alkyl or side chain.

Question 16

Aldehydes

Accepted Answer

The group without R is called the aldehyde group or formyl group. Aldehydes differ from ketones in that the carbonyl is placed at the end of a carbon skeleton rather than between two carbon atoms.

Question 17

Many aldehydes have pleasant odours

Accepted Answer

The double bond between carbon and oxygen is characteristic of all aldehydes and is known as the carbonyl group.

Question 18

aldehyde condensed structural formulas

Accepted Answer

?CHO. Using this convention, the formula of formaldehyde is HCHO and that of acetaldehyde is CH3CHO

Question 19

The functional group of an alcohol is the -OH (hydroxyl) group

Accepted Answer

true

Question 20

The parent name of an alcohol is the name of the longest carbon chain that contains the -OH group.

Accepted Answer

true

Question 21

In the IUPAC system, the presence of three -OH groups is shown by the ending -triol.

Accepted Answer

true

Question 22

Because of the presence of an -OH group, all alcohols are polar compounds.

Accepted Answer

true

Question 23

The boiling point of alcohols increase with increasing molecular weight.

Accepted Answer

true

Question 24

What is the difference in structure between a primary, a secondary, and a tertiary alcohol?

Accepted Answer

The difference is in the number of carbon atoms bonded directly to the carbon bearing the -OH group. For primary alcohol, there is zero or one carbon group; for a secondary alcohol, there are two, and for a tertiary alcohol, there are three.

Question 25

Explain in terms of noncovalent interactions why the low molecular weight alcohols are soluble in water but the low molecular    weight alkanes and alkynes are not

Accepted Answer

Low molecular weight alcohols form hydrogen bonds with water molecules through both the oxygen and hydrogen atoms of their - OH groups, and because of this association, they dissolve in water. Low molecular weight alkanes, alkenes, and alkynes are nonpolar compounds and do not associate in any way with water molecules.     The large amount of hydrogen bonding between an alcohol molecule and water molecules makes the low molecular weight alcohol soluble in water. Low molecular weight alkanes, alkenes, and alkynes are insoluble in water.

Question 26

Why does the water solubility of low molecular weight alcohols decrease as molecular weight increases

Accepted Answer

As the molecular weight of an alcohol increase, the hydrocarbon part of the molecule becomes a larger and larger part of its surface area. In other words, as the hydrocarbon portion increases, the nonpolar region of the compound increases as well. The physical properties of alcohols, including their solubility in water, then become more like those of hydrocarbons of similar carbon skeletons.

Question 27

-propanol (isopropyl alcohol) is commonly used as rubbing alcohol to cool the skin. 2-hexanol, also a liquid, is not suitable for   this purpose. Why?

Accepted Answer

The cooling effect comes from evaporation. 2-hexanol\'s boiling point is too high to be easily evaporated from the skin.

Question 28

. The two most important reactions of alcohols are their acid-catalyzed dehydration to give alkenes and their   oxidation to aldehydes, ketones, and carboxylic acids.

Accepted Answer

true

Question 29

The acidity of alcohols is comparable to that of water.

Accepted Answer

true

Question 30

Acetic acid, CH3COOH, can be prepared from ethylene, CH2=CH2 by treatment with K2Cr2O7/H2SO4

Accepted Answer

true

Question 31

Show how to distinguish between cyclohexanol and cyclohexene by a simple chemical test. Tell what you would do, what you   would expect to see, and how you would interpret your observations.

Accepted Answer

Cyclohexene will react with bromine (a reddish-purple liquid) to give 1,2-dibromocyclohexane, which has no color. Cyclohexanol does not react with bromine. Therefore, the liquid that causes the reddish-purple of bromine to disappear must be cyclohexene.

Question 32

The functional group of thiol is the -SH (sulfhydryl) group

Accepted Answer

true

Question 33

The parent name of thiol is the name of the longest carbon chain that contains the -SH group.

Accepted Answer

true

Question 34

thiol

Accepted Answer

Organic compounds containing sulfhydryl groups.

Question 35

The S - H bond is nonpolar covalent.

Accepted Answer

true

Question 36

The acidity of ethanethiol is comparable to that of phenol.

Accepted Answer

true

Question 37

Both phenols and thiols are classified as weak acids

Accepted Answer

true

Question 38

Explain why glycerol is much thicker (more viscous) than ethylene glycol, which in turn is much thicker than ethanol.

Accepted Answer

The thickness (viscosity) of these three liquids is related to the degree of hydrogen bonding between their molecules in the liquid state. Hydrogen bonding is strongest between molecules of glycerol, weaker between molecules of ethylene glycol, and weakest between molecules of ethanol.

Question 39

The acidity of ethanethiol is comparable to that of phenol.

Accepted Answer

true

Question 40

Both phenols and thiols are classified as weak acids.

Accepted Answer

true

Question 41

The most common biological reaction of thiols is their oxidation to disulfides

Accepted Answer

true

Question 42

The functional group of a disulfide is the - S - S - group.

Accepted Answer

true

Question 43

Explain why methanethiol, CH3SH, has a lower boiling point (6oC) than methanol, CH3OH (65oC), even though methanethiol has a   higher molecular weight

Accepted Answer

Molecules of methanol, in the liquid state, associate by hydrogen bonding. Molecules of methanethiol, in the liquid state, associate only by the considerably weaker London dispersion forces. Because of the stronger intermolecular forces of attraction between its molecules, methanol has a higher boiling point than methanethiol.

Question 44

Today, the major carbon sources for the synthesis of methanol are coal and methane (natural gas), both nonrenewable resources.

Accepted Answer

true

Question 45

. Intermolecular acid-catalyzed dehydration of ethanol gives diethyl ether.

Accepted Answer

true

Question 46

. Conversion of ethylene to ethylene glycol involves oxidation to ethylene oxide, followed by acid-catalyzed    hydration (addition of water) to ethylene oxide

Accepted Answer

true

Question 47

Ethylene glycol is soluble in water in all proportions.

Accepted Answer

true

Question 48

A major use of ethylene glycol is as automobile antifreeze.

Accepted Answer

true

Question 49

. The one aldehyde and the one ketone with a molecular formula of C3H6O are constitutional isomers. True   .b. Aldehydes and ketones both contain a carbonyl group True   c. The VSEPR model predicts bond angles of 120o about the carbonyl carbon of aldehydes and ketones. True   d. The carbonyl carbon of a ketone is a stereocenter. False

Accepted Answer

. What is the difference in structure between an aromatic aldehyde and an aliphatic aldehyde?   The carbonyl carbon of an aldehyde is bonded to, at least, one hydrogen. The carbonyl carbon of a ketone is bonded to two carbon groups.

Question 50

a. An aldehyde is named as an alkanal, and a ketone is named as an alkanone. True   b. The names for aldehydes and ketones are derived from the name of the longest carbon chain   that contains the carbonyl carbon. True   c. In an aromatic aldehyde, the carbonyl carbon is bonded to an aromatic ring. True

Accepted Answer

a. The reduction of an aldehyde always gives a primary alcohol. True   b. The reduction of a ketone always gives a secondary alcohol. True   c. The oxidation of an aldehyde gives a carboxylic acid. True   d. The oxidation of a primary alcohol gives a ketone. False   e. Tollen\'s reagent can be used to distinguish between an aldehyde and a ketone. True   f. Sodium borohydride, NaBH4, reduces an aldehyde to a primary alcohol. True   g. The addition of one molecule of alcohol to the carbonyl group of a ketone gives a hemiacetal. True   h. The reaction of an aldehyde with two molecules of alcohol gives an acetal, plus a molecule of water. True   i. The formation of hemiacetals and acetals is reversible. True   j. The cyclic hemiacetal formed form 4-hydroxypentanal has two stereocenters and can exist as a mixture    of 22 = 4 stereoisomers. True

Question 51

Acetone is completely soluble in water, but 4-heptanone is completely insoluble in water. Explain.

Accepted Answer

The carbonyl group of acetone forms hydrogen bonds with water. These hydrogen bonds are sufficient to make acetone in any proportions soluble in water. 4-heptanone contains a carbonyl group, which through its hydrogen bonding with water molecules, promotes water solubility. It also contains two 3-carbon hydrocarbon groups bonded to the carbonyl carbon, which inhibit hydrocarbon groups bonded

Question 52

Pentane, 1-butanol, and butanal all have approximately the same molecular weights but different boiling points. Arrange them in order of increasing boiling point. Explain the basis for your ranking.

Accepted Answer

Pentane is a nonpolar hydrocarbon, and the only attractive forces between its molecules in the liquid state are the very weak London dispersion forces. Pentane, therefore, has the lowest boiling point. Butanal and 1-butanol are both polar molecules. Because 1-butanol has a polar -OH group, its molecules can associate by hydrogen bonding. The intermolecular attraction between molecules of 1-butanol is greater than those between molecules of butanal. 1-butanol, therefore, has a higher boiling point than butanal.

Question 53

a. The reduction of an aldehyde always gives a primary alcohol. True   b. The reduction of a ketone always gives a secondary alcohol. True   c. The oxidation of an aldehyde gives a carboxylic acid. True   d. The oxidation of a primary alcohol gives a ketone. False   e. Tollen\'s reagent can be used to distinguish between an aldehyde and a ketone. True   f. Sodium borohydride, NaBH4, reduces an aldehyde to a primary alcohol. True

Accepted Answer

The addition of one molecule of alcohol to the carbonyl group of a ketone gives a hemiacetal. True   h. The reaction of an aldehyde with two molecules of alcohol gives an acetal, plus a molecule of water. True   i. The formation of hemiacetals and acetals is reversible. True   j. The cyclic hemiacetal formed form 4-hydroxypentanal has two stereocenters and can exist as a mixture    of 22 = 4 stereoisomers. True

Question 54

What is the characteristic structural feature of a hemiacetal? Of an acetal?

Accepted Answer

The characteristic structural feature of a hemiacetal is a carbon atom bonded to an -OH group and either an -OR or    an -OAr group. The characteristic structural feature of an acetal is a carbon atom bonded to two -OR or -OAr groups.

Question 55

hemiacetal

Accepted Answer

When an aldehyde reacts with an alcohol, a_________is formed.

Question 56

What is the difference in meaning between the terms \"hydration\" and \"hydrolysis\"? Give an example of each.

Accepted Answer

Hydration refers to the addition of one or more molecules of water to a substance. An example of hydration is the acid-catalyzed addition of water to propene to give 2-propanol.

Question 57

Hydrolysis refers to the reaction of a substance with water

Accepted Answer

generally with the breaking (lysis) of one or more bonds in the substance. An example of hydrolysis is the acid-catalyzed reaction of an acetal with a molecule of water to give an aldehyde or ketone and two molecules of alcohol. Another example of hydrolysis is the reverse of Fischer esterification (Chapter 18), namely the hydrolysis of an ester to give a carboxylic acid and an alcohol.

Question 58

The general name of an aliphatic carboxylic acid is alkanoic acid. True   b. The molecule containing two COOH groups is called a dicarboxylic acid. True   c. Ethanedioic acid (oxalic acid) is the simplest decarboxylic acid. True   d. 3-methylbutanoic acid is chiral. False

Accepted Answer

. The simplest carboxylic acid is methanoic acid (formic acid), HCOOH. True   f. Benzoic acid is an aromatic carboxylic acid. True   g. Formic acid, which is the common name for HCOOH, is derived from the word formica, which is the Latin   name for ants. True   h. (S)-lactic acid, CH3-CHOH-COOH contains two functional groups: a 2o alcohol and a carboxyl group. True

Question 59

Define and give an example of Fischer Esterification.

Accepted Answer

Fischer esterification is the process of forming an ester by treating a carboxylic acid with an alcohol in the presence of an acid catalyst, commonly sulfuric acid. An example is the formation of ethyl ethanoate from ethanoic acid and ethanol

Question 60

With three areas of electron density around a carbonyl carbon, the VSEPR theory predicts a bond angle of 120o.

Accepted Answer

A trigonal planar atom cannot be a stereocenter. An atom that is a stereocenter must have four different    substituents bonded to it.

Question 61

Carboxylic acids do not oxidize any further with chromic acid. The conversion of a carboxylic acid to an alcohol is   actually a reduction reaction that is accomplished with lithium aluminum hydride (LiAlH4) followed by the addition   of an aqueous acid.

Accepted Answer

The functional groups of a carboxylic acid are a carbonyl group bonded to a hydroxyl group. True

Question 62

structural and physical properties of alcohol.

Accepted Answer

The electronegativity of oxygen contributes to the unsymmetrical distribution of charge, creating a partial positive charge on the hydrogen and a partial negative charge on the oxygen. This uneven distribution of electron density in the O-H bond creates a dipole. Also, because of the high electronegativity of oxygen relative to that of carbon, the O-H bond is shorter

Question 63

apply IUPAC nomenclature and common names to alcohols.

Accepted Answer

Substitutive names of alcohols are developed by identifying the longest continuous chain that bears the hydroxyl group and replacing the -e ending of the corresponding alkane by the suffix -ol.

Question 64

Alcohols occur with primary, secondary and tertiary structures. Whether an alcohol is primary, secondary or tertiary depends on the number of hydrogens attached to the carbon atom bearing the -OH group, as shown in the below figure. These differences in structure affect the way the alcohols react.

Accepted Answer

?Primary alcohols have two hydrogens on the OH-bearing carbon - this carbon is bonded to one other carbon.  ?Secondary alcohols have two carbons and only one hydrogen substituted onto the OH-bearing carbon.  ?Tertiary alcohols have three carbons and no hydrogens on the OH-bearing carbon

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