Page 289 - Theory and Problems of BEGINNING CHEMISTRY

278 ORGANIC CHEMISTRY [CHAP. 18

Supplementary Problems

18.42. Define or identify each of the following terms: (a) organic chemistry, (b) total bond order, (c) condensed formula,
(d ) structural formula, (e) line formula, ( f ) hydrocarbon, (g) alkane, (h) alkene, (i) alkyne, ( j ) aromatic hydrocarbon,
(k ) saturated, (l) delocalized double bond, (m) isomerism, (n) cycloalkane, (o) radical, ( p) functional group, (q)
alcohol, (r) ether, (s) aldehyde, (t) ketone, (u) carbonyl group, and (v) ester.
Ans. See the Glossary.

18.43. What is the total bond order of oxygen in all aldehydes, alcohols, ketones, acids, amides, and ethers?
Ans. 2

18.44. What is the smallest number of carbon atoms possible in a molecule of (a) a ketone, (b) an aldehyde, and (c)an
aromatic hydrocarbon?
Ans. (a) 3 (A molecule cannot have a “middle” carbon atom unless it has at least three carbon atoms.) (b)1
(c)6
18.45. In which classes of compounds can the R group(s) be a hydrogen atom?
Ans. Acids, amides, amines (two maximum), and esters (R on the oxygen atom cannot be H),

18.46. (a) Which classes of compounds contain the element grouping C O?(b) In which is it the entire functional
group?
Ans. (a) Aldehydes, ketones, acids, amides, and esters (b) Aldehydes and ketones

18.47. Which of the following is apt to be the stronger acid, FCOOH or HCOOH? Explain.
Ans. The electrons in the OH bond are attracted away from the hydrogen atom more by the F atom in FCOOH than
by the H atom in HCOOH, since F is more electronegative than H. The H atom on the O atom in FCOOH
is therefore easier to remove; that is, it is more acidic.
18.48. Urea and thiourea have formulas NH 2 CONH 2 and NH 2 CSNH 2 .(a) Explain why they are considered to be organic
compounds. (b) Explain why they do not fit the general definition given in Sec. 18.1.
Ans. (a) Urea is a product of animal metabolism, and thiourea is its sulfur analog. (b) Both hydrogen atoms
of their “parent,” formaldehyde, H 2 CO, have been replaced with amino groups, and there are no C Cor
C H bonds left.

18.49. In the formula CH 3 CH 2 OCOCH 3 , which oxygen atom is double-bonded?
Ans. The double-bonded oxygen is conventionally written after the carbon atom to which it is attached, so the
second oxygen is double-bonded to the carbon. The condensed formula is
CH 3 CH 2 O C CH 3

O

18.50. Using toothpicks and marshmallows or gumdrops, make a model of butane. The angles between the toothpicks must
be 109.5 . Show that the following represent the same compound:
◦
C C C C C
C C
C C C C C C C C C
18.51. Give the name of the class of organic compound represented by each of the following: (a)CH 3 COCH 3 ,
(b)CH 3 OCH 2 CH 3 ,(c)CH 3 CO 2 CH 3 ,(d )CH 3 CH 3 ,(e)CH 3 CO 2 H, (f )CH 3 CHO, (g)CH 3 CH 2 OH, (h)CH 2 CHCH 3 ,
and (i)CH 3 NH 2 .
Ans. (a) Ketone (b) Ether (c) Ester (d ) Alkane (e) Acid (f ) Aldehyde (g) Alcohol (h) Alkene (i) Amine