CHEM 219 Organic Chemistry Module 5
Exam 2024 with complete solution
What are hydrocarbons? - -----ANSWER---->Molecules composed of only the elements carbon and
hydrogen
What are the two major classes of hydrocarbons? - -----ANSWER---->Aromatic (benzene) and aliphatic
(alkanes, alkenes, alkynes)
What is the main source of hydrocarbons? - -----ANSWER---->Fossil fuels like coal, petroleum, and natural
gas obtained by mining and drilling.
What are Alkanes? - -----ANSWER---->They are saturated hydrocarbons because their skeleton is only
composed of C-C single bonds.
How can alkanes exist? - -----ANSWER---->They can be linear, branched or exist in ring formations called
cycloalkanes.
Describe a higher/more complex alkane structure: - -----ANSWER---->They will have more carbons and/or
increased structural diversity.
What is the general formula of Alkanes? - -----ANSWER---->CnH2n+2
The names of the alkanes reflect? - -----ANSWER---->The number of carbons present.
How many isomers does each alkane have from 1-10 - -----ANSWER---->1,1,1,2,3,5,9,18,35,75
,Name the first ten prefix of alkanes: - -----ANSWER---->Methane, ethane, propane, butane, pentane,
hexane, heptane, octane, nonane, decane.
As the molecular weight increases: - -----ANSWER---->The number of isomers increase.
What does the suffix -ane mean? - -----ANSWER---->Denotes a saturated hydrocarbon. It is used for all
acyclic saturated alkanes
What is nomenclature? - -----ANSWER---->The naming of a molecular structure. Historically they were
named after their source, now they are systemic.
Why is nomenclature important? - -----ANSWER---->Because we cannot remember all the prefixes since a
MF composed of carbons can have several different patterns of connectivity.
What is it meant by the systemic approach? - -----ANSWER---->There are now methods of naming
molecules so that they all have unique names. You can then determine the structure from only the name
and vice-versa.
IUPAC rules for naming branced alkanes: - -----ANSWER---->1. Find the parent name by identifying the
longest continuous chain of carbons.
2. Number the parent chain. (begin at the end of the chain nearest to the first branch.)
3. If there are two equally long continuous chains, select the one with most branches.
4. If the first branch point is the same distance, choose the one that gives the lowest substituents.
5. If the substituents are both equidistant then choose the numbering so the substituent goes with the
higher alphabetic priority.
How are linear alkanes named? - -----ANSWER---->By combining the prefix indicating the number to the
suffix -ane.
What is a substituent? - -----ANSWER---->Any group attached to the parent chain.
What are alkyl groups? - -----ANSWER---->Saturated hydrocarbon substituents. You drop the -yl for -ane.
,A one carbon substituent is a methyl group, four carbon is butyl.
What is a locant? - -----ANSWER---->A number used to determine the suffix.
Describes the position of substituents.
What happens when two or more of the same type of substituents are present on the parent chain? Like
3 methyl groups - -----ANSWER---->Additional prefixes including the number are added.
How would you describe finding 2,3 dimethylpentane? - -----ANSWER---->It is a 5 carbon chain, then it
has substituents on numbers 2, 3 and those are methyl groups.
How are IUPAC systematic names put together? - -----ANSWER---->Locant-(prefix) substituentparent
If two or more different substituents are present on the parent chain then what happens? - -----ANSWER-
--->They are listed alphabetically. Ethyl before methyl
How are halogen atoms as substituents named? - -----ANSWER---->Change the -ine to -o,
chlorine=chloro, bromine=bromo.
propyl or n-propyl - -----ANSWER---->CH3CH2CH2
isopropyl - -----ANSWER---->CH3CHCH3
What does the squiggle bond mean? - -----ANSWER---->Point of attachment to the parent chain.
Butyl or n-butyl - -----ANSWER---->-CH2CH2CH2CH3
sec-butyl - -----ANSWER---->CH3CHCH2CH3
isobutyl - -----ANSWER---->
, tert-butyl - -----ANSWER---->
Isobutyl would be alphabetized as? While sec-butyl would be alphabetized as? - -----ANSWER---->I, B
What does R represent? - -----ANSWER---->It is a generic/wildcard notation in organic structure.
Any alkyl group.
This is known as R-group notation.
Why is R chosen? - -----ANSWER---->It is not on the chart anywhere.
What is the important thing to know about the physical properties of alkanes. - -----ANSWER---->They
will show similar trends in terms of their physical properties.
What does the physical properties of a molecule refer to? - -----ANSWER---->Characteristics like melting
point, boiling point, density, solubility.
How do you compare the boiling point of alkanes? - -----ANSWER---->The longer the length of carbon,
the higher the Boiling point. When it is branched, it can have a higher boiling point, as long as it isn't the
parent chain that is branched.
Are alkanes soluble in water? - -----ANSWER---->They are water-insoluble.
Are alkanes polar or non-polar? - -----ANSWER---->Almost non-polar
What is hydrogen bonding? - -----ANSWER---->The water molecules are attracted to each other like
magnets because of it's electron rich O atom possessing a -charge and its electron poor H possessing a +
charge
What will a mixture of alkane and water make? - -----ANSWER---->A two layer-biphasic system. It will
float on top of water. since its density is less than 1g/ml
Exam 2024 with complete solution
What are hydrocarbons? - -----ANSWER---->Molecules composed of only the elements carbon and
hydrogen
What are the two major classes of hydrocarbons? - -----ANSWER---->Aromatic (benzene) and aliphatic
(alkanes, alkenes, alkynes)
What is the main source of hydrocarbons? - -----ANSWER---->Fossil fuels like coal, petroleum, and natural
gas obtained by mining and drilling.
What are Alkanes? - -----ANSWER---->They are saturated hydrocarbons because their skeleton is only
composed of C-C single bonds.
How can alkanes exist? - -----ANSWER---->They can be linear, branched or exist in ring formations called
cycloalkanes.
Describe a higher/more complex alkane structure: - -----ANSWER---->They will have more carbons and/or
increased structural diversity.
What is the general formula of Alkanes? - -----ANSWER---->CnH2n+2
The names of the alkanes reflect? - -----ANSWER---->The number of carbons present.
How many isomers does each alkane have from 1-10 - -----ANSWER---->1,1,1,2,3,5,9,18,35,75
,Name the first ten prefix of alkanes: - -----ANSWER---->Methane, ethane, propane, butane, pentane,
hexane, heptane, octane, nonane, decane.
As the molecular weight increases: - -----ANSWER---->The number of isomers increase.
What does the suffix -ane mean? - -----ANSWER---->Denotes a saturated hydrocarbon. It is used for all
acyclic saturated alkanes
What is nomenclature? - -----ANSWER---->The naming of a molecular structure. Historically they were
named after their source, now they are systemic.
Why is nomenclature important? - -----ANSWER---->Because we cannot remember all the prefixes since a
MF composed of carbons can have several different patterns of connectivity.
What is it meant by the systemic approach? - -----ANSWER---->There are now methods of naming
molecules so that they all have unique names. You can then determine the structure from only the name
and vice-versa.
IUPAC rules for naming branced alkanes: - -----ANSWER---->1. Find the parent name by identifying the
longest continuous chain of carbons.
2. Number the parent chain. (begin at the end of the chain nearest to the first branch.)
3. If there are two equally long continuous chains, select the one with most branches.
4. If the first branch point is the same distance, choose the one that gives the lowest substituents.
5. If the substituents are both equidistant then choose the numbering so the substituent goes with the
higher alphabetic priority.
How are linear alkanes named? - -----ANSWER---->By combining the prefix indicating the number to the
suffix -ane.
What is a substituent? - -----ANSWER---->Any group attached to the parent chain.
What are alkyl groups? - -----ANSWER---->Saturated hydrocarbon substituents. You drop the -yl for -ane.
,A one carbon substituent is a methyl group, four carbon is butyl.
What is a locant? - -----ANSWER---->A number used to determine the suffix.
Describes the position of substituents.
What happens when two or more of the same type of substituents are present on the parent chain? Like
3 methyl groups - -----ANSWER---->Additional prefixes including the number are added.
How would you describe finding 2,3 dimethylpentane? - -----ANSWER---->It is a 5 carbon chain, then it
has substituents on numbers 2, 3 and those are methyl groups.
How are IUPAC systematic names put together? - -----ANSWER---->Locant-(prefix) substituentparent
If two or more different substituents are present on the parent chain then what happens? - -----ANSWER-
--->They are listed alphabetically. Ethyl before methyl
How are halogen atoms as substituents named? - -----ANSWER---->Change the -ine to -o,
chlorine=chloro, bromine=bromo.
propyl or n-propyl - -----ANSWER---->CH3CH2CH2
isopropyl - -----ANSWER---->CH3CHCH3
What does the squiggle bond mean? - -----ANSWER---->Point of attachment to the parent chain.
Butyl or n-butyl - -----ANSWER---->-CH2CH2CH2CH3
sec-butyl - -----ANSWER---->CH3CHCH2CH3
isobutyl - -----ANSWER---->
, tert-butyl - -----ANSWER---->
Isobutyl would be alphabetized as? While sec-butyl would be alphabetized as? - -----ANSWER---->I, B
What does R represent? - -----ANSWER---->It is a generic/wildcard notation in organic structure.
Any alkyl group.
This is known as R-group notation.
Why is R chosen? - -----ANSWER---->It is not on the chart anywhere.
What is the important thing to know about the physical properties of alkanes. - -----ANSWER---->They
will show similar trends in terms of their physical properties.
What does the physical properties of a molecule refer to? - -----ANSWER---->Characteristics like melting
point, boiling point, density, solubility.
How do you compare the boiling point of alkanes? - -----ANSWER---->The longer the length of carbon,
the higher the Boiling point. When it is branched, it can have a higher boiling point, as long as it isn't the
parent chain that is branched.
Are alkanes soluble in water? - -----ANSWER---->They are water-insoluble.
Are alkanes polar or non-polar? - -----ANSWER---->Almost non-polar
What is hydrogen bonding? - -----ANSWER---->The water molecules are attracted to each other like
magnets because of it's electron rich O atom possessing a -charge and its electron poor H possessing a +
charge
What will a mixture of alkane and water make? - -----ANSWER---->A two layer-biphasic system. It will
float on top of water. since its density is less than 1g/ml
