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CHEM 219 MODULE 2 EXAM NEWEST ACTUAL EXAM PREPARATION
WITH COMPLETE QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES | ALREADY GRADED A+||BRAND NEW VERSION!!
What is the relationship between branching and VDWF? - ANSWER-As you
branch out you gain more surface area and lower the VDWF. Which lowers
the BP and MP
Alkanes can adopt different conformations, What does this mean? -
ANSWER-This means that it can change shapes as it can rotate around
bonds.
Hydrogen bonding and VDWFS are classifies as nonbonding intermolecular
forces, what does this mean? - ANSWER-That they are attractive forces
between molecules that are not true bonds in the sense of sharing or
donating.
What are conformers? - ANSWER-Different shapes of molecules that are
derived by rotations of single bonds.
What does the Newman projection do? - ANSWER-It shows the
conformation of molecules when looking down a particular bond axis.
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What is the difference in hydrogen placement between an eclipsed
confirmation and a staggered one? - ANSWER-The hydrogens do not
overlap in staggered but they do in eclipsed.
Certain conformers are called rotamers, why? - ANSWER-They can simply
be rotated into the other conformer. Used with newman projections
Staggered vs. Eclipsed Conformers - ANSWER-Staggered are generally
more stable, because of the removed repulsion that occurs when electrons
are aligned on top of each other in an eclipsed.
How do you name newman projections? - ANSWER-Find the first carbon
chain, attach it to the front carbon. The rest are substituents. Then attach it
to the back carbon. Then attach the first carbon chain, the rest are
substituents.
Can conformers be isolated at room temp? - ANSWER-No, because theres
a lot of thermal energy, it starts the rapid inter conversion of conformers.
Meaning it rotates back and forth
What are cycloalkanes? - ANSWER-Alkanes whose carbon skeleton forms
a ring. (only c-c sigma bonds)
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Cycloalkanes that have 1 ring has the general formula of? - ANSWER-
Cn+H2n
How are cycloalkanes named? - ANSWER-With the prefix cyclo- in front of
the corresponding alkane name
What is the systemic approach when alkyl substituents are present? -
ANSWER-1. If only one substituent is present then no locants (numbers) are
used.
2. If more than one is present. It is put in order
What is angle strain? - ANSWER-When bond angles deviate from their ideal
values by being stretched or compressed
What is torsional strain? - ANSWER-When cyclic molecules must assume
conformations that have eclipsed interactions
What is ring strain? - ANSWER-Angle strain + Torsional strain. Ring strain
destabilizes the molecule and so the molecule tries to adopt a conformational
structure to minimize the strain energy.
CHEM 219 MODULE 2 EXAM NEWEST ACTUAL EXAM PREPARATION
WITH COMPLETE QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES | ALREADY GRADED A+||BRAND NEW VERSION!!
What is the relationship between branching and VDWF? - ANSWER-As you
branch out you gain more surface area and lower the VDWF. Which lowers
the BP and MP
Alkanes can adopt different conformations, What does this mean? -
ANSWER-This means that it can change shapes as it can rotate around
bonds.
Hydrogen bonding and VDWFS are classifies as nonbonding intermolecular
forces, what does this mean? - ANSWER-That they are attractive forces
between molecules that are not true bonds in the sense of sharing or
donating.
What are conformers? - ANSWER-Different shapes of molecules that are
derived by rotations of single bonds.
What does the Newman projection do? - ANSWER-It shows the
conformation of molecules when looking down a particular bond axis.
,2|Page
What is the difference in hydrogen placement between an eclipsed
confirmation and a staggered one? - ANSWER-The hydrogens do not
overlap in staggered but they do in eclipsed.
Certain conformers are called rotamers, why? - ANSWER-They can simply
be rotated into the other conformer. Used with newman projections
Staggered vs. Eclipsed Conformers - ANSWER-Staggered are generally
more stable, because of the removed repulsion that occurs when electrons
are aligned on top of each other in an eclipsed.
How do you name newman projections? - ANSWER-Find the first carbon
chain, attach it to the front carbon. The rest are substituents. Then attach it
to the back carbon. Then attach the first carbon chain, the rest are
substituents.
Can conformers be isolated at room temp? - ANSWER-No, because theres
a lot of thermal energy, it starts the rapid inter conversion of conformers.
Meaning it rotates back and forth
What are cycloalkanes? - ANSWER-Alkanes whose carbon skeleton forms
a ring. (only c-c sigma bonds)
, 3|Page
Cycloalkanes that have 1 ring has the general formula of? - ANSWER-
Cn+H2n
How are cycloalkanes named? - ANSWER-With the prefix cyclo- in front of
the corresponding alkane name
What is the systemic approach when alkyl substituents are present? -
ANSWER-1. If only one substituent is present then no locants (numbers) are
used.
2. If more than one is present. It is put in order
What is angle strain? - ANSWER-When bond angles deviate from their ideal
values by being stretched or compressed
What is torsional strain? - ANSWER-When cyclic molecules must assume
conformations that have eclipsed interactions
What is ring strain? - ANSWER-Angle strain + Torsional strain. Ring strain
destabilizes the molecule and so the molecule tries to adopt a conformational
structure to minimize the strain energy.
