Ochem unit 4

Select the correct IUPAC name for the following alkane: 2-methyl-5-sec-butylhexane 3,4,7-trimethyloctane 2,5,6-trimethyloctane 2-ethyl-3,6-dimethylheptane

2,5,6-trimethyloctane

atch the structure of each alkyl group to its correct IUPAC name.

-CH2CH3: ethyl -CH2CH2CH2CH3: butyl -CH3: methyl -CH2CH2CH2CH2CH3 : pentyl

elect the correct IUPAC name for the following cycloalkane: 1-methyl-2-ethylcyclopentane 1-methyl-5-ethylcyclopentane 1-ethyl-5-methylcyclopentane 1-ethyl-2-methylcyclopentane

1-ethyl-2-methylcyclopentane

Carbon substituents that are bonded to a long carbon chain are known as _____ groups. alkyl alkenyl alkane alkynyl

alkyl

Alkanes contain only C-C and C-H bonds, which are _____. As a result, they exhibit only ____ van der forces, which are much ____ than dipole-dipole forces. The melting and boiling points of these compounds are therefore ____ than the melting and boiling points of polar compounds of comparable size.

Blank 1: nonpolar or non-polar Blank 2: Waals or waals Blank 3: weaker Blank 4: lower or less

To name a simple cycloalkane, the number of carbon atoms in the ring gives ____ the name and the prefix ____ is added before this part of the name.

Blank 1: parent or root Blank 2: cyclo

An alkyl group is named according to the number of C atoms it contains. An alkyl group with three carbon atoms joined in a straight chain is called a(n) ____ group, whereas a methyl group has ____ carbon atom(s).

Blank 1: propyl Blank 2: one or 1

The most and least stable conformations of ethane are shown. Conformer A in which the C-H bonds on one carbon bisect the H-C-H bond angle on the adjacent carbon is called a _____ conformation. B is the _____ conformation, in which the C-H bonds of one carbon are directly aligned with the C-H bonds on the adjacent carbon.

Blank 1: staggered Blank 2: eclipsed

Straight-chain alkanes are named according to the number of C atoms in the chain. Match each name to the correct chain length.

2C - ethane 5C - pentane 7C - heptane 9C - nonane

Match each structure shown to its correct IUPAC name.

A: 3,4-dimethylnonane B: 2,7-dimethylnonane C: 5-ethyl-3-methylnonane D: 3-ethyl-7-methylnonane

Nearly half of a barrel of crude oil is used for _____. Petroleum starting materials for chemical synthesis jet fuel diesel and home heating oil gasoline

gasoline Reason: Approximately 20 out of 42 gallons of crude oil is used to make gasoline.

_____ nomenclature is a set of rules used to assign a _____ name to a compound. Multiple choice question.

IUPAC; systematic

Consider the two conformers of fluoroethane shown. Conformer A is ____ stable than conformer B and the energy of conformer A is ____than the energy of conformer B.

Blank 1: less Blank 2: higher, greater, or more

Any alkane has at least two different conformations of different energy. A lower energy conformation is converted to a higher energy conformation by rotation about a ____ bond. In order for this rotation to occur there must be sufficient energy to overcome the ___ barrier between the conformations.

Blank 1: single, sigma, or carbon-carbon sigma Blank 2: energy, rotation, or rotational

The Newman projections for four conformations of 2-methylpentane, shown as viewed down the C2-C3 bond, are provided. Match each conformation with its expected position on a graph of dihedral angle vs. energy.

Conformer A - local energy maximum Conformer B - overall energy minimum (lowest energy) Conformer C - overall energy maximum (highest energy) Conformer D - local energy minimum

Which conformation of butane (shown) possesses the greatest amount of steric strain? Conformer A Conformer B Conformer C Conformer D

Conformer C

he Newman projections of four conformers of pentane, drawn as viewed down the C2-C3 bond, are shown. Match each conformer with the correct description of the types of strain it exhibits. Instructions

Structure A - maximum torsional and steric strain Structure B - no torsional strain, no steric strain Structure C - maximum torsional strain, no steric strain Structure D - no torsional strain, some steric strain

An increase in energy that results from atoms being forced too close to one another is called _____ strain, while an increase in energy caused by eclipsing interactions is called _____ strain. steric, torsional torsional, steric

steric, torsional Reason: Torsional strain is an increase in energy due to eclipsing interactions.

Click and drag on elements in order Place the following alkanes in order of decreasing melting point, based on their structures. Place the compound with the highest mp at the top of the list.

B C A

Place the following alkanes in order of decreasing melting point, based on their structures. Place the compound with the highest mp at the top of the list.

B C A

Match each type of name for a drug molecule with its correct description.

Systematic - Chemical name assigned according to IUPAC conventions Generic - Official international name of the drug Trade - Brand name assigned by the manufacturer

Match each type of name for the given drug with its correct description.

Systematic: 2-acetoxybenzoic acid Generic: acetylsalicylic acid Trade: Aspirin

Select all the statements that correctly interpret the Newman projection shown. This compound has a total of 3 carbon atoms. The Cl atom is attached to the front carbon atom. The hydrogen marked "b" is on the back carbon atom. The hydrogen marked "a" is on the back carbon atom.

The Cl atom is attached to the front carbon atom. The hydrogen marked "a" is on the back carbon atom.

Alkanes can be cyclic or acyclic. Match each type of alkane to the corresponding general molecular formula. acyclic alkane cycloalkane

acyclic alkane - CnH2n+2 cycloalkane - CnH2n

A carbon substituent in an organic compound is called a(n) _____ group. carboxyl alkyl hydrocarboxyl

alkyl

Match each structure in the diagram with its common name.

basketane - A churchane - B cubane - C housane - D

The IUPAC name of the compound shown is ___ (C5H10)

cyclopentane

Which of the following is a polycyclic alkane composed of 12 five-membered rings? housane cubane churchane dodecahedrane

dodecahedrane Reason: Churchane consists of 7 rings total. Reason: Cubane consists of 6 four-membered rings Reason: Housane consists 7 rings total.

Match the description of each conformation with the correct term.

eclipsed conformation - Bonds on adjacent C atoms are aligned. staggered conformation - Bonds on one C bisect the bond angles on the adjacent C atom.

Eclipsing interactions result from electron-electron repulsion between electrons in σ bonds. Repulsion is at a maximum when bonds are _____ and minimized when bonds are _____. A staggered conformer is therefore _____ stable than an eclipsed conformer. staggered, eclipsed, more eclipsed, staggered, more eclipsed, staggered, less staggered, eclipsed, less

eclipsed, staggered, more

Select all statements that correctly describe the composition of a barrel of crude oil (42 gallons). gasoline (19.7 gallons) asphalt and road oil (1.3 gallons) lubricants, waxes and solvents (21 gallons) jet fuel (4.2 gallons)

gasoline (19.7 gallons) asphalt and road oil (1.3 gallons) jet fuel (4.2 gallons) Reason: Lubricants, waxes, and solvents make up only a small portion of a barrel of crude oil (4.2 gallons).

A group of compounds that differ by only a CH2 group is called a _____. homozygous series homogeneous series homologous series

homologous series

Constitutional or structural isomers have _____ molecular formulas and _____ connectivities of their atoms. identical; identical different; identical different; different identical; different

identical; different

Click and drag on elements in order Place the following alkanes in order of increasing boiling point, based on their structures. Start with the compound that has the lowest boiling point at the top of the list.

A C B

Select all the statements that correctly describe the IUPAC rules for naming an alkane. -Each substituent must be numbered, even if there are two or more of the same group in the compound. -The parent name is obtained by finding the longest continuous carbon chain. -The prefix tri is used to indicate that there are three identical alkyl groups attached to the longest chain. -The parent chain is numbered from left to right.

- Each substituent must be numbered, even if there are two or more of the same group in the compound. - The parent name is obtained by finding the longest continuous carbon chain. - The prefix tri is used to indicate that there are three identical alkyl groups attached to the longest chain.

Select the statement that correctly defines a homologous series. -A series or group of structural isomers. -A series of different representations for the same compound. -A group of compounds that differ by one CH2 group in the structure. -The branched structural isomers of a straight-chain alkane.

-A group of compounds that differ by one CH2 group in the structure. Reason: A homologous series is a series of compounds that differ by one CH2 group. CH3CH2CH3, CH3CH2CH2CH3, and CH3CH2CH2CH2CH3 form a homologous series

Select all the statements that correctly describe the composition of alkanes. -Alkanes contain only C and H atoms. -Alkanes are classified as aliphatic hydrocarbons. -Alkanes contain C=C double bonds. -Alkanes are always acyclic compounds. -Cycloalkanes have two fewer H atoms than acyclic alkanes.

-Alkanes contain only C and H atoms. -Alkanes are classified as aliphatic hydrocarbons. -Cycloalkanes have two fewer H atoms than acyclic alkanes.

Select all the statements that correctly describe the bonding in an alkane such as ethane (shown). -Each H atom is sp3 hybridized. -All C-C bonds are single bonds. -Each C atom is sp3 hybridized. -Each C atom has a planar geometry with 90° bond angles.

-All C-C bonds are single bonds. -Each C atom is sp3 hybridized. -Reason: An H atom cannot be hybridized. -Reason: Each C is tetrahedral with 109.5o bond angles.

How many carbon atoms are there in the longest continuous carbon chain in the structure shown? 4 5 6 8

6 Reason: Chains that are 4, 5, and 6 carbons long can be identified in this molecule; the longest is 6.

What is the correct IUPAC name of the alkane shown? 4-ethyl-2-propyloctane 4-methyl-6-ethyldecane 6-ethyl-4-methyldecane 3-butyl-5-methyloctane 4-methyl-6-butyloctane

6-ethyl-4-methyldecane

What is the correct IUPAC name of the alkane shown?

6-ethyl-4-methyldecane Reason: Substituents should be named in alphabetical order.

Select all the statements that correctly describe how to name a cycloalkane. If there is an alkyl chain containing more C atoms than there are in the ring, the ring is named as a cycloalkyl substituent. The name of a cycloalkane ends with the suffix -cyclane. The parent name is given by the number of carbon atoms in the ring. If there is a single substituent on the ring there is no need to specify its position. For a ring with two different substituents, the ring is numbered to give the substituent with the least number of C atoms the lowest possible number.

-If there is an alkyl chain containing more C atoms than there are in the ring, the ring is named as a cycloalkyl substituent. -The parent name is given by the number of carbon atoms in the ring. -If there is a single substituent on the ring there is no need to specify its position.

Select all the statements that correctly describe a pair of structural isomers. -Structural isomers are also called constitutional isomers. -Structural isomers differ by one CH2 group. -Structural isomers have different molecular formulas. -Structural isomers are different compounds. -Structural isomers differ in the way their atoms are connected to each other.

-Structural isomers are also called constitutional isomers. -Structural isomers are different compounds. -Structural isomers differ in the way their atoms are connected to each other.

Select all statements that correctly describe the systematic naming of organic compounds. -The systematic name indicates the compound's chemical structure. -The systematic naming of compounds is referred to as the IUPAC system of nomenclature. -A trade name is the official, internationally approved name for a drug. -Systematic names are always short and concise.

-The systematic name indicates the compound's chemical structure. -The systematic naming of compounds is referred to as the IUPAC system of nomenclature.

Rank the following conformations in order of increasing stability (less stable at the top of the list).

1. eclipsed 2. staggered

Place the steps for naming an acyclic alkane in the correct order.Place the first step at the top of the list and the last step at the bottom of the list.

1. find the parent carbon and add the suffix 2. number the atoms in the parent carbon chain 3. name and number the substituents 4. combine substituent names and numbers + parent +suffix

Straight-chain alkanes are named according to the number of C atoms in the chain. Match each name to the correct chain length.

1C - methane 3C - propane 4C - butane 6C - hexane

Select the alkane name that has the correct format. 3-ethyl-2,6-dimethylheptane 2-methyl-3-ethyl-6-methylheptane 2,6-dimethyl-3-ethylheptane 3-ethyl-2,6-dimethyl-heptane

3-ethyl-2,6-dimethylheptane Reason: The correct name of this compound is 3-ethyl-2,6-dimethylheptane. There are two identical methyl substituents and a multiplying prefix should be used. Reason: The correct name of this compound is 3-ethyl-2,6-dimethylheptane. The prefix di is ignored when alphabetizing the substituents. Reason: Hyphens are only used to separate numbers from letters.

Select the correct IUPAC name for the alkane shown: 2-methyl-3-ethylhexane 3-isopropylhexane 3-ethyl-2-methylhexane 2-methyl-3-propylpentane

3-ethyl-2-methylhexane

Select all the statements that correctly describe the procedure for drawing a Newman projection. A Newman projection considers one C-C bond at a time. The bonds for both the front and back C atoms are drawn as lines meeting at the center of the circle. There will be 3 lines drawn directly to each C atom. A dot drawn at the center of the circle represents the front C. A circle is used to represent the back carbon.

A Newman projection considers one C-C bond at a time. There will be 3 lines drawn directly to each C atom. A dot drawn at the center of the circle represents the front C. A circle is used to represent the back carbon.

Select the statement that correctly describes the relationship between the structures A and B (shown). -A and B are identical because B is produced by the rotation of a single bond in A. -A and B are different because the spatial arrangement of their atoms is different. -A and B are different compounds because B is formed by breaking a bond and forming a new one.

A and B are identical because B is produced by the rotation of a single bond in A. Reason: A and B are the same compound since they have the same connectivity of atoms.

Match the value of the dihedral angle to the conformations shown.

A: 60 degrees B: 0 degrees

Select all the statements that correctly describe the physical properties of alkanes. Alkanes have lower boiling points than polar compounds of comparable size. The melting points of normal alkanes generally increase as the number of C atoms in the chain increases. Alkanes are nonpolar compounds. The boiling point of alkane isomers increases with branching in the chain. Alkanes with more than 5 carbons tend to be soluble in water.

Alkanes have lower boiling points than polar compounds of comparable size. The melting points of normal alkanes generally increase as the number of C atoms in the chain increases. Alkanes are nonpolar compounds. Reason: The bp of isomers decreases with branching because of decreased surface area. Reason: Nonpolar alkanes are insoluble in water.

Select all the statements that correctly describe the bonding in an alkane such as ethane (shown was C2H6). -Each H atom is sp3 hybridized. -All C-C bonds are single bonds. -Each C atom has a planar geometry with 90° bond angles. -Each C atom is sp3 hybridized.

All C-C bonds are single bonds. Each C atom is sp3 hybridized.

Any carbon substituent formed by removing one hydrogen from an alkane (for example, CH3CH2CH2-) is called a(n) ___ group.

Blank 1: alkyl

A cycloalkane is named by adding the prefix ___ to the name of the acyclic alkane that has the same number of ____ atoms.

Blank 1: cyclo Blank 2: carbon or C

A cycloalkane is named by adding the prefix _____ to the name of the acyclic alkane that has the same number of ____ atoms.

Blank 1: cyclo Blank 2: carbon or C

The angle that separates a bond on one atom from a bond on an adjacent atom is called a ____ angle. For a pair of eclipsed bonds (as in the conformation shown) the value of this angle is ____ degrees.

Blank 1: dihedral Blank 2: zero or 0

Electron-electron repulsion between electrons in σ bonds is at a maximum in the eclipsed conformation. These electron-electron interactions are also known as _____ interactions. The increase in energy that results is called ____ strain.

Blank 1: eclipsing Blank 2: torsional

In an alkane all C atoms are surrounded by____ individual groups and are therefore _____ hybridized with a ____ geometry.

Blank 1: four or 4 Blank 2: sp3 Blank 3: tetrahedral

C-C σ bonds allow _____ rotation about the bond, which places the substituents on the carbon atoms into different 3-D orientations with respect to each other. These different 3-D arrangements are called ___ .

Blank 1: free or complete Blank 2: conformations or conformers

A staggered conformation in which two larger groups are 600 from each other is called a(n) _____ conformation, whereas a staggered conformation in which two larger groups are 180o from each other is called a(n) ____ conformation.

Blank 1: gauche Blank 2: anti

Consider the two conformers of fluoroethane shown. Conformer A is _____ stable than conformer B and the energy of conformer A is ____ than the energy of conformer B.

Blank 1: less Blank 2: higher, greater, or more

An alkane parent chain is always numbered to give the first substituent the ___ number. If the first substituent is the same distance from both ends the chain is numbered to give the ___ substituent the lowest possible number.

Blank 1: lowest, smallest, or lower Blank 2: second, next, following, or 2nd

Which of the following is a methylene group? CH3 CH CH2

CH2 CH3 is a methyl group. CH is a methine group

Which of the following is the correct molecular formula for a cycloalkane? CnHn CnH2n CnH2n+2

CnH2n Reason: CnH2n+2 is the molecular formula for an alkane. Reason: CnHn is the molecular formula for an alkyne.

Select all the statements that correctly describe the different conformations of a compound. Conformations are different compounds with different physical properties. Conformations interconvert by rotation about σ bonds. Conformations are different arrangements of atoms that are interconverted by rotation about single bonds. The conformations of a compound are not all equally stable.

Conformations interconvert by rotation about σ bonds. Conformations are different arrangements of atoms that are interconverted by rotation about single bonds. The conformations of a compound are not all equally stable.

Select all the conformations of 2-methylbutane that will be energy maxima in a graph of dihedral angle vs. energy. Conformer A Conformer B Conformer C Conformer D

Conformer A Conformer D

The Newman projections for three conformers of butane are shown. Match each conformer with the term that describes the relationship between the CH3 groups.

Conformer A - staggered anti Conformer B - staggered gauche Conformer C - eclipsed

Select all the statements that correctly describe how to number the parent chain of an alkane. If the first substituent is the same distance from both ends, the chain is numbered to give the second substituent the lowest number. The chain is numbered to give the first substituent the lowest number. The chain is numbered to give the highest number to the first substituent. The chain is numbered from left to right. The chain is numbered so that the lowest number is given to the substituent that is first alphabetically.

If the first substituent is the same distance from both ends, the chain is numbered to give the second substituent the lowest number. The chain is numbered to give the first substituent the lowest number.

Which of the following are abbreviations used for common alkyl groups? Me t-Bu s-Bu Py Et

Me t-Bu Et

Match each common alkyl group shown to its appropriate abbreviation.

Me: -CH3 t-Bu: -C(CH3)3 Bu: -CH2CH2CH2CH3 Et: -CH2CH3

elect the correct IUPAC name for the cycloalkane shown. 6-isopropylcyclohexane isopropylcyclohexane 2-propylcyclohexane propylcyclohexane

Reason: If a cycloalkane has only one substitutent, its position is not numbered, since all positions are equivalent. The substituent is an isopropyl group, not a propyl group.

True or false: Alkyl groups are formed by removing one hydrogen from an alkane. True/False

True Reason: Carbon substituents bonded to a long carbon chain are called alkyl groups.

Select all statements that correctly describe the stability of eclipsed and staggered conformers. Electron-electron repulsion between bonds in an eclipsed conformer may contribute to the low energy of this conformer. Staggered conformers possess torsional strain. Staggered conformers are lower in energy than eclipsed conformers. Eclipsed conformers possess torsional strain.

Staggered conformers are lower in energy than eclipsed conformers. Eclipsed conformers possess torsional strain. Reason: Torsional strain is an increase in energy caused by eclipsing interactions and is only found in eclipsed conformers. Reason: Electron-electron repulsion between bonds in an eclipsed conformer may contribute to the high energy of this conformer.

Select the correct definition for steric strain. Steric strain is an increase in energy caused by the repulsion between electrons in σ bonds that are eclipsed. Steric strain is an increase in energy caused by the repulsion between the H atoms on adjacent carbons. Steric strain is an increase in energy caused by two atoms being forced too close to one another. Steric strain is an increase in energy caused by the repulsion between nonbonded electrons in a molecule.

Steric strain is an increase in energy caused by two atoms being forced too close to one another. Reason: Torsional strain is an increase in energy caused by the repulsion between electrons in σ bonds that are eclipsed

Select all the structures that represent structural isomers (constitutional isomers) of 2-methylpentane (shown). Structure A Structure B Structure C Structure D

Structure A Structure C Reason: A and C are isomers of 2-methylpentane since they have the same formula (C6H14) but a different skeletal arrangement of atoms. Reason: B and D are identical to 2-methylpentane since they have the same formula and skeletal arrangement of atoms.

Select all the structures from the following options that represent branched alkanes. Structure A Structure B Structure C Structure D

Structure A Structure D a branched alkane is an "n-alkane" ex. propane is C5H12. (a non-branded alkane), both 2-methylpropane & 2,2-dimethylpropane are structural isomers of propane w/ the same chemical formula, but different branched structures.

Match each IUPAC name to the correct alkane structure.

Structure A: 2,3-dimethylpentane Structure B: 4-ethyl-2-methylhexane Structure C: 2,2-dimethylpropane

Match the structure of each branched alkyl group with its correct name. Structure A Structure B Structure C Structure D

Structure A: sec-butyl Structure B: tert-butyl Structure C: isopropyl Structure D: isobutyl

Which of the following is the correct Newman projection for the staggered conformer of bromoethane? Structure A Structure B Structure C Structure D

Structure B

Select the structure that represents a structural isomer of compound X Structure A Structure B Structure C Structure D

Structure B Reason: A & C is identical to compound X, since they have the same molecular formula and connectivity of atoms.

Which one of the following is NOT an equivalent representation of structure 1 Structure A Structure B Structure C Structure D

Structure B -Reason: B is a structural isomer (constitutional isomer) of 1.

Select all the options that give the correct structure for the IUPAC name 4-ethyl-2,3-dimethylheptane. Structure A Structure B Structure C Structure D

Structure B Structure C

Select the statement that correctly describes the procedure used to select the parent chain of an alkane if there are two different chains of the same length. The chain with fewer substituents is the parent chain. The chain that is drawn with fewer bends is the parent chain. Both chains may be designated as the parent. The chain with more substituents is the parent chain.

The chain with more substituents is the parent chain.

Select all statements that correctly describe the format for the name of an alkane. Substituents are named in the order of their numerical location on the parent chain. A hyphen is placed between the name of the last substituent and the parent name, e.g., 3-methyl-octane. The substituent numbers and names appear at the front of the parent name. If there are two or more of the same substituent the prefixes di, tri, etc. are used. Commas are used to separate two consecutive numbers in the name.

The substituent numbers and names appear at the front of the parent name. If there are two or more of the same substituent the prefixes di, tri, etc. are used. Commas are used to separate two consecutive numbers in the name.

True or false: Alkanes exhibit only weak van der Waals intermolecular forces. True/False

True Reason: Alkanes contain only nonpolar C-H and C-C bonds and exhibit only weak van der Waals forces.

Match the type of butyl substituent with the appropriate description of how the group is formed from an alkane. isobutyl group tert-butyl group sec-butyl group

isobutyl group - Removal of a 1° H from 2-methylpropane (shown) tert-butyl group - Removal of a 3° H from 2-methylpropane (shown) sec-butyl group - Removal of a 2° H from butane (shown)

The alkyl substituent shown here is a(n) _____ group. isopropyl propyl 2-methylpropane iso-propyl

isopropyl Reason: A propyl substituent would have the point of attachment at one end of the chain. This is an isopropyl group.

Consider the graph of energy vs. dihedral angle for conformations of ethane. When the dihedral angle between any two hydrogens is 0o, the energy of the system is at a _____. At a dihedral angle of 60o, the energy of the system is at a ______. maximum; maximum maximum; minimum minimum; maximum minimum; minimum

maximum; minimum Reason: Energy is at a maximum at 0o, then decreases to a minimum at 60o.

Natural gas is composed largely of ____ (60-80% depending on its source).

methane

What is the principal component of natural gas? methane ethane butane propane

methane

A CH2 group is also called a ___ group.

methylene

Staggered conformers are _____ stable than eclipsed conformers due to the _____ of _____ strain in eclipsed conformers. Multiple choice question. less; absence; torsional more; presence; steric more; presence; torsional less; absence; steric

more; presence; torsional

If an alkane has two different chains of equal length, the longest continuous chain with the _____ substituents is selected as the parent chain. fewest most

most

Which types of intermolecular forces affect the physical properties of alkanes? (Select all that apply.) both van der Waals forces and dipole-dipole interactions only van der Waals forces both hydrogen bonding and dipole-dipole interactions only hydrogen bonding only dipole-dipole interactions both van der Waals forces and hydrogen bonding

only van der Waals forces

The systematic name for every organic compound has three parts. Select the correct description for each part of the name. prefix suffix parent name

prefix - identity, location, and number of substituents suffix - functional group or class of compound parent name - number of C atoms in the longest continuous C chain

A C-C bond with a barrier to rotation of 12 KJ/mol rotates _____ enough that different conformations _____ be separated at room temperature. slowly; cannot quickly; can quickly; cannot slowly; can

quickly; cannot Reason: A barrier to rotation of 12 KJ/mol is very small, and the bond would rotate very quickly at room temperature. Different rotamers cannot be separated from one another.

The name of a _____-butyl group is derived by the removal of a _____ hydrogen. sec; 2˚ tert; 3˚ quat; 4˚ iso; 2˚

sec; 2˚ tert; 3˚ Reason: An isobutyl group does not contain a hyphen in the name, but it is derived by removal of a 1˚ hydrogen from 2-methylpropane. Reason: There is no such group called a quat-butyl group. It is also not possible for a hydrogen to be 4˚ since a 4˚ has no hydrogens bonded to it.

The difference in energy between the staggered and eclipsed conformations of ethane is _____ with the result that rotation about the C-C σ bond is _____. The different conformations _____ be separated at room temperature. small, rapid, cannot large, slow, can small, slow, cannot large, rapid, can

small, rapid, cannot Reason: If the energy barrier were large, the σ bond rotation would not be rapid and the conformations would be easily separable.

Consider the graph of energy vs. dihedral angle for conformations of ethane. The energy minima shown on the graph correspond to _____ rotamers. The energy maxima on the graph correspond to _____ rotamers. torsional; steric steric; torsional staggered; eclipsed eclipsed; staggered

staggered; eclipsed

The functional group present in an organic molecule is indicated by the _____ of the name, whereas the _____ indicates the identity, location, and number of substituents attached to the carbon chain. suffix; prefix suffix; parent prefix; suffix prefix; parent

suffix; prefix

The type of strain that results from repulsion between the electrons in eclipsed σ bonds is called _____ strain. torsional sigma conformational steric

torsional Reason: Steric strain is an increase in energy resulting when atoms are forced too close to one another.

Newman projections are given for two of the conformers of 2-methylbutane, drawn as viewed down the C2-C3 bond. In A the _____ strain is at a maximum due to the eclipsing of bonds. In B this strain is minimized but there is still _____ strain due to the proximity of the bulky CH3 groups that are _____ to each other. torsional; steric; anti torsional; steric; gauche steric; torsional; gauche steric; torsional; anti

torsional, steric, gauche