Chem 219: Module 2 Exam Questions and Answers
Grade A+
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.
Grade A+
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.
