new way chemistry for hong kong a-level book 3a1 worksheet-01-answers introduction to organic...
Post on 21-Dec-2015
227 Views
Preview:
TRANSCRIPT
New Way Chemistry for Hong Kong A-Level Book 3A1
Worksheet-01-Answers
Introduction to Organic Chemistry
Chem-160-Summer-2015
New Way Chemistry for Hong Kong A-Level Book 3A2Dr Seemal Jelani2
21.1 What is Organic Chemistry (SB p.4)
(a)How was organic chemistry defined before 1800s? Answer
(a) The knowledge of organic and inorganic
compounds was raised during the 1780s.
Scientists defined organic chemistry as the
study of compounds that could be obtained
from living organisms. They believed that the
synthesis of organic compounds took place in
living organisms only.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A3Dr Seemal Jelani3
21.1 What is Organic Chemistry (SB p.4)
(b) How is organic chemistry defined nowadays?
Back
Answer(b) Nowadays, scientists have discovered that
many organic compounds can be synthesized
from inorganic substances. The updated
definition of organic chemistry is the study of
carbon compounds, except for carbon
monoxide, carbon dioxide, carbonates,
hydrogencarbonates, carbides and cyanides.
These compounds have been traditionally
classified under inorganic chemistry.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A4Dr Seemal Jelani4
21.2 The Unique Nature of Carbon (SB p.5)
Why is carbon able to catenate?
Back
AnswerThe ability to catenate of carbon is chiefly due to
the high strength of the CC single bond (bond
enthalpy of C C single bond is 356 kJ mol-1).
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A5Dr Seemal Jelani5
21.2 The Unique Nature of Carbon (SB p.6)
Would you expect silicon, which is just below carbon in the Periodic Table, to catenate to form diverse molecular structures? Explain your answer. Answer
Silicon, unlike carbon, does not catenate to form diverse
molecular structures. Carbon is able to catenate because
carbon atoms have a relatively small atomic size. This
enables a carbon atom to form strong covalent bonds
with other carbon atoms. However, due to the greater
atomic size of silicon, its ability to catenate is much lower
than that of carbon.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A6Dr Seemal Jelani6
21.2 The Unique Nature of Carbon (SB p.7)
Would you expect sulphur, which has an electronegativity value very close to carbon, to catenate? Why?
Back
Answer
The electronic configuration of sulphur is 1s22s22p63s23p4. It
has only two unpaired electrons. Its atomic size is larger than
that of carbon. So it has a much lower tendency to catenate
than carbon.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A7Dr Seemal Jelani7
21.3 Classification of Organic Compounds (SB p.14)
Identify the functional group(s) in the following compounds:
(a)
Answer(a) Carbon-carbon double bond ( ) and
chloro group (Cl)
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A8Dr Seemal Jelani8
21.3 Classification of Organic Compounds (SB p.14)
Identify the functional group(s) in the following compounds:
(b)
Answer(b) Carbonyl group ( )
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A9Dr Seemal Jelani9
21.3 Classification of Organic Compounds (SB p.14)
Identify the functional group(s) in the following compounds:
(c)
Answer(c) Amino group ( ) and carboxyl group
( )
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A10Dr Seemal Jelani10
21.3 Classification of Organic Compounds (SB p.15)
To which homologous series does each of the following compounds belong?
(a)
Answer
(a) Ester
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A11Dr Seemal Jelani11
21.3 Classification of Organic Compounds (SB p.15)
To which homologous series does each of the following compounds belong?
(b)
Answer
(b) Amide
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A12Dr Seemal Jelani12
21.3 Classification of Organic Compounds (SB p.15)
To which homologous series does each of the following compounds belong?
(c)
Answer
(c) Acid anhydride
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A13Dr Seemal Jelani13
21.3 Classification of Organic Compounds (SB p.15)
State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answer.
(a)
Answer(a) No, the first one is a carboxylic acid and the
second one is an ester.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A14Dr Seemal Jelani14
21.3 Classification of Organic Compounds (SB p.15)
State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answer.
(b)
Answer(b) Yes, both of them are alcohols.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A15Dr Seemal Jelani15
21.3 Classification of Organic Compounds (SB p.15)
State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answer.
(c)
Answer(c) No, the first one is an amide and
the second one is an amine.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A16Dr Seemal Jelani16
21.3 Classification of Organic Compounds (SB p.16)
(a) Name the homologous series of organic compounds that contain oxygen atoms in their functional groups. Answer(a) Alcohol, ether, aldehyde, ketone,
carboxylic acid, ester, acyl halide,
amide and acid anhydride
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A17Dr Seemal Jelani17
21.3 Classification of Organic Compounds (SB p.16)
(b) Identify and name the functional groups in glucose which has the following structure.
Answer
(b) OH (hydroxyl group)
and O (oxy group)
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A18Dr Seemal Jelani18
21.3 Classification of Organic Compounds (SB p.16)
(c) Identify and name the functional groups in the following compounds:
Answer
Back
(c) Br (bromo),
(aldehyde),
(acyl chloride),
(carbon-carbon
double bond) groups
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A19Dr Seemal Jelani19
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.18)
Why is oil immiscible with water?
AnswerOil molecules do not have free OH groups,
so they cannot form hydrogen bonds with
water molecules.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A20Dr Seemal Jelani20
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.20)
The relative molecular mass of glucose is 180.0, but it is soluble in water. Why?
AnswerGlucose molecules have OH groups, so
they are able to form hydrogen bonds with
water molecules. Therefore, glucose is
soluble in water despite it has a high
molecular mass. Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A21Dr Seemal Jelani21
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.20)
Despite the fact that butan-1-ol and ethoxyethane have the same relative molecular mass, they have very different boiling points. The boiling points of butan-1-ol and ethoxyethane are 117oC and 35oC respectively. Explain the difference. Answer
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A22Dr Seemal Jelani22
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.20)
There is an OH group in butan-1-ol. Thus, butan-1-ol molecules are
able to form hydrogen bonds with one another and the energy required to
separate butan-1-ol molecules would be much greater. Whereas for
ethoxyethane, the attraction among the molecules is weak van der
Waals’ forces only. The amount of energy required to break the forces
would not be great. Therefore, the boiling point of ethoxyethane is lower
than that of butan-1-ol.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A23Dr Seemal Jelani23
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.21)
Explain why propan-1-ol is soluble in water but
1-chloropropane is insoluble in water.
AnswerThe OH group of propan-1-ol molecules enables it to form
hydrogen bonds with water molecules. Thus it is soluble in water.
Although 1-chloropropane is a polar molecule, it does not form
hydrogen bonds with water molecules. So it is insoluble in water.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A24Dr Seemal Jelani24
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.21)
Which molecule would have a higher boiling point, 1-bromobutane or 2-bromobutane? Why?
Answer1-bromobutane would have a higher boiling point.
1-bromobutane is a straight-chain molecule while
2-bromobutane is a branched-chain molecule. Straight-chain
molecules have a greater surface area in contact with each
other, so greater intermolecular forces exist among the
molecules. Higher energy is required to break down the
intermolecular forces among the molecules of 1-bromobutane.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A25Dr Seemal Jelani25
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.22)
1-Chlorobutane and 2-chloro-2-methylpropane have the same molecular mass, yet their melting points differ. The melting point of 1-chlorobutane is –123oC while that of 2-chloro-2-methylpropane is –27.1oC. Explain the difference.
Answer
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A26Dr Seemal Jelani26
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.22)
Melting point is a measure of how efficient the molecules are packed
together in the solid state instead of just comparing the van der
Waals’ forces among molecules. Hence melting point is a function of
the efficient packing of molecules but not the contact surface area.
1-Chlorobutane is a straight-chain molecule while
2-chloro-2-methylpropane is a branched-chain molecule. As
2-chloro-2-methylpropane is more spherical and symmetrical, its
molecules are packed more efficiently in the solid state.
1-Chlorobutane is linear in shape and flattened, its packing in the
solid state is not so efficient. Hence, it has a lower melting point than
2-chloro-2-methylpropane.
Back
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A27Dr Seemal Jelani27
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(a) What are the major factors that affect the physical properties of organic compounds?
Answer(a) The physical properties of organic compounds
are mainly affected by the structure of the
functional groups, dipole moment of the
molecule, the formation of hydrogen bonding
between molecules, and the length of carbon
chains of the molecule.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A28Dr Seemal Jelani28
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(b) The melting point and boiling point of pentane are –130oC and 36.3oC respectively while the melting point and boiling point of 2,2-dimethylpropane are –15.9oC and 9.5oC respectively. Account for the difference in melting point and boiling point between the two isomers.
Answer
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A29Dr Seemal Jelani29
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(b) Pentane is a straight-chain molecule, while 2,2-dimethylpropane
is a branched-chain molecule. Straight-chain molecules have a
greater surface area in contact with each other than branched-
chain molecules. Straight-chain molecules are held together by
stronger intermolecular forces. Therefore, pentane has a higher
boiling point than 2,2-dimethylpropane. Molecules of 2,2-
dimethylpropane are more spherical in shape and are packed
more efficiently in the solid state. Molecules of pentane are linear
in shape and flattened, so their packing in the solid state is not
efficient. Since extra energy is required to break down the efficient
packing of 2,2-dimethylpropane, 2,2-dimethylpropane has a
higher melting point than pentane.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A30Dr Seemal Jelani30
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(c) Which molecule, hexane or cyclohexane, would have a higher melting point? Explain your answer.
Answer04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A31Dr Seemal Jelani31
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(c) Cyclohexane has a higher melting point than hexane. Molecules
of cyclohexane are more spherical in shape and are packed more
eff iciently in the solid state. Molecules of hexane are linear in
shape and flattened, so their packing in the solid state is not
efficient. Since extra energy is required to break down the efficient
packing of cyclohexane, cyclohexane has a higher melting point
than hexane.
04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A32Dr Seemal Jelani32
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(d) Arrange the following molecules in increasing order of boiling points. Explain your answer.
Answer04/19/23
New Way Chemistry for Hong Kong A-Level Book 3A33Dr Seemal Jelani33
21.4 Factors Affecting the Physical Properties of Organic Compounds (SB p.24)
(d) The boiling points increase in the order:
butane < propanal < propan-1-ol
Molecules of butane are non-polar. Their molecules are held
together by weak instantaneous dipole-induced dipole
interactions. A relatively small amount of energy is required to
separate the molecules in the process of boiling. Both propanal
and propan-1-ol are polar molecules. Molecules of propanal are
held together by relatively weak dipole-dipole interactions, while
molecules of propan-1-ol are held together by intermolecular
hydrogen bonds. Since the intermolecular forces present in
molecules of propan-1-ol are stronger than those present in
molecules of propanal, a larger amount of energy is required to
separate the propan-1-ol molecules in the process of boiling.
Back
04/19/23
top related