Chemistry Chapter 11, 12, 13

Dimethyl sulfide, CH₃SCH₃, is a thioether used as an organic reducing agent in certain reactions and is known for its unpleasant smell. Draw the Lewis structure of CH₃SCH₃ and then determine the number of lone pairs of electrons on sulfur

2 lone pairs

How many carbon atoms are present in 2,3-dimethyl-2-pentene?

7

Which molecular formula corresponds to an alkyne? A) C₈H₁₄ B) C₆H₁₄ C) C₁₀H₂₂ D) C₃H₆ E) C₂H₆

A) C₈H₁₄ Due to the presence of a triple bond, alkynes have four fewer hydrogens than the corresponding saturated, alkane CnH2n+2 and will adopt the general formula CnH2n−2, where n is any number equal to two or greater. C₈H₁₄ shares this general formula indicating it can be an alkyne.

Which of the following functional groups is NOT present in morphine (shown below)? A) ether B) alcohol C) alkene D) amide E) amine

An amide contains a -C(=O)-N- functional group and morphine is lacking this structural arrangement of atoms.

The reaction of 2-pentyne with excess hydrogen gas in the presence of Pd produces what compound? A) 2-pentene B) pentane C) 1-pentyne D) cis-2-pentene E) 2-pentanol

An excess of hydrogen gas in the presence of Pd will add two hydrogen molecules to the triple bond, reducing it completely to a single bond. The product will be pentane.

Consider the intermolecular forces present in a pure sample of each of the following compounds: CH₃Cl and CCl₄. Identify the intermolecular forces that these compounds have in common. A) Dispersion forces, dipole-dipole forces, and hydrogen bonding. B) Dispersion forces only. C) Dispersion forces and dipole-dipole forces. D) Dipole-dipole forces only.

Both CH3Cl and CCl4 molecules experience dispersion forces (as do all molecules). CH3Clhas polar C-Cl bonds and a net dipole in the molecule. Therefore dipole-dipole forces are possible. However, CCl4 has polar C-Cl bonds that are symmetrically located resulting in no net dipole in the molecule. Therefore no dipole-dipole forces are possible. Neither molecule exhibits hydrogen bonding, which requires a hydrogen atom attached to an F, O or N atom.

Consider the intermolecular forces present in a pure sample of each of the following compounds: CH₃OH and CF₄. Identify the intermolecular forces that these compounds have in common.

Both CH3OH and CF4 molecules experience dispersion forces (as do all molecules). CH3OH has a polar C-O bond and a net dipole in the molecule. Dipole-dipole forces are possible for this molecule. However, CF4 has polar C-F bonds that are symmetrically located resulting in no net dipole in the molecule. Therefore no dipole-dipole forces are possible for this molecule. Only CH3OH has the feature which can exhibit hydrogen bonding, a hydrogen atom attached to an F, O or N atom.

Which of the following intermolecular forces are present in a pure sample of CH₃CH₃? I. Dispersion forces II. Dipole-dipole interactions III. Hydrogen bonding A) I only B) I and II only C) I and III only D) I, II and III

CH3CH3 is a nonpolar molecule. Nonpolar molecules interact with other molecules through dispersion forces only.

Which of the following polymers represents a polyester? A) Compound I B) Compound II C) Compound III D) Compound IV

Compound IV. Polymers are classified by their monomeric subunits. This structure is polyethylene terephthalate (PET), one of the most common plastics used in everyday life, which has repeating ester subunits.

The molecules cis-2-butene and trans-2-butene are _____ A) identical molecules. B) stereoisomers. C) constitutional isomers. D) isotopes. E) molecular isomers.

Constitutional Isomers

Which molecular formula corresponds to a straight-chain alkane? A) C₄H₆ B) C₄H₈ C) C₅H₁₀ D) C₅H₁₂ E) C₆H₁₂

C₅H₁₂ adopts the general formula of an alkane CnH2n+2CnH2n+2 which corresponds to a saturated hydrocarbon like a straight-chain alkane that has the maximum number of hydrogen atoms (2n+2) for the given number of carbon atoms (n)

Which molecular formula corresponds to an alkene? A) C₆H₁₀ B) C₇H₁₄ C) CH₄ D) C₁₀H₂₂ E) C₂H₆

C₇H₁₄ Due to the presence of a double bond, alkenes have two fewer hydrogens than the corresponding saturated, alkane CnH2n+2 and will adopt the general formula CnH2n, where n is any number equal to two or greater. C₇H₁₄ shares this general formula indicating it can be an alkene.

What intermolecular forces are mostly responsible for the melting point and boiling point of an alkene? A) ionic B) hydrogen bonding C) dispersion D) dipole-dipole E) ion-dipole

Dispersion There are no ions, polar bonds, or electronegative atoms available for hydrogen bonding in alkenes, so the intermolecular forces must be dispersion forces.

How many hydrogen atoms are present in 2-methyl-2-butene?

Draw the structure of the compound. The general formula of an alkene is CnH2n. There are five total carbon atoms and thus there are 10 hydrogen atoms.

The complete combustion of two moles of 2-methylpropane would yield how many moles of carbon dioxide (CO₂)?

Eight moles of carbon dioxide (CO₂) would be produced. According to the balanced chemical equation for the complete combustion of two moles of 2-methylpropane, which has a molecular formula of C₄H₁₀, eight moles of carbon dioxide are produced. 2 C₄H₁₀ (g) + 13 O₂ (g)→ 8 CO₂ (g) + 10 H₂O (g)

Which of the following is expected to have the highest boiling point? A) CH₄ B) CH₃Cl C) CH₃OH D) C₂H₆

For molecules of approximately the same size, the strength of the intermolecular forces present will be the best predictor of the boiling point. CH3OH is a polar molecule that forms hydrogen bonds, while the strongest intermolecular forces in the other molecules are dipole-dipole attraction or dispersion forces. Since hydrogen bonding is a strong intermolecular force, CH3OH has the highest boiling point.

What is the arrangement of the bromine substituents in the organic compound shown? A) ortho B) meta C) para D) cis E) trans

Groups that are arranged in the 1,3 positions are referred to as meta. Ortho groups are in the 1,2 positions, and para groups are in the 1,4 positions. Cis and trans do not refer to positions in an aromatic ring like benzene.

What reagents are required to convert alkene 1-propene to the haloalkane 2-bromopropane? A) HBr B) H₂O, H₂SO₄ C) Br₂ D) H₂

HBr will add to the double bond of 1-propene, with H adding to C1 and Br adding to C2 to form 2-bromopropane.

In a ___________ reaction, the components of water (H-OH) are added across a carbon-carbon double bond (C=C). A) hydration B) hydrogenation C) bromination D) combustion E) elimination

Hydration reaction. A hydration reaction involves adding the components of water (H-OH) across a carbon-carbon double or triple bond.

Which of the following substances would not exhibit any hydrogen bonding interactions in a pure substance?

Hydrogen bonding results when a hydrogen atom is covalently bonded to the highly electronegative N, O, or F atoms, resulting in a large partial positive charge on the H atom. Since N(CH3)3 is the only option without H bonded directly to N, O, or F (here, there are only C-H bonds), it would not exhibit hydrogen bonding.

What reagents are required to convert the alkene 1-butene to the alkane butane? A) Br₂ B) H₂ with Pd-C C) H₂O, H₂SO₄ D) HBr

H₂ will add to the double bond of 1-butene, with H adding to C1 and H adding to C2 to form butane. Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation

Identify the functional groups present in ibuprofen. A) phenol and ketone B) carboxylic acid and phenol C) carboxylic acid and benzene ring D) alcohol, ketone and benzene ring

Ibuprofen contains a carboxylic acid and benzene ring. A carboxylic acid has the structure -COOH, which is a carbonyl group (C=O) bound to a carbon atom on one side and a hydroxy group (-OH) on the other side. A benzene ring contains carbon-carbon double bonds (C=C) within a six-membered ring, which has a flat structure.

Which of the following compounds can exist as cis-trans isomers? A) 2-methyl-1-butene B) 2-methyl-2-butene C) 3-methyl-1-butene D) 2-pentene E) 1-pentene

In order for cis-trans isomerism to exist, two nonidentical groups must be located on each carbon atom of the double bond. 2-pentene has two nonidentical groups, one methyl and one hydrogen group on one of the carbon atoms of the double bond, with the other carbon of the double bond containing one hydrogen and one propyl group resulting in cis-trans isomers being possible.

Determine the name of the following aromatic compound. A) fluorobenzene B) 1-fluorobenzene C) 2-fluorobenzene D) benzene fluoride E) benzyl fluoride

Monosubstituted benzene compounds will use benzene as the root and add the appropriate substituent as the prefix and do not indicate its position on the ring. Only one fluorine (-F) is present to give the name fluorobenzene.

What reagents are required to accomplish the following reaction? (Benzene to Nitrobenzene) A) HNO₃ B) H₂SO₄ C) HNO₃, H₂SO₄, heat D) NH₃, O₂ E) HNO₃, NH₃

Nitration of benzene requires not only the nitrating reagent, HNO₃, but also a strong acid and heat.

Draw the Lewis structure of formaldehyde (H₂CO).

POLAR

A hydrocarbon is referred to as __________ if all the bonds in the molecule are single bonds. A) aromatic B) saturated C) unsaturated D) planar E) octahedral

Saturated

Draw the Lewis structure of acetaldehyde (CH₃CHO) and then choose the appropriate pair of molecular geometries of the two central atoms. Your answer choice is independent of the orientation of your drawn structure.

Tetrahedral/Tri Planar

Draw the Lewis structure of methanol (CH₃OH) and then choose the appropriate pair of molecular geometries of the two central atoms. Your answer choice is independent of the orientation of your drawn structure.

Tetrahedral/bent

Which of the following has the lowest boiling point? A) C₅H₁₂ B) C₇H₁₆ C) C₉H₂₀ D) C₁₁H₂₄ E) C₁₃H₂₈

The boiling point is the temperature at which a substance will change from the liquid to the gas phase, so compounds with weaker intermolecular forces will have lower boiling points. Since all of these options are nonpolar, their only intermolecular forces are dispersion forces, which are smaller for compounds with fewer electrons. Of these options, C5H12 has the fewest electrons, so it has the weakest intermolecular forces and therefore the lowest boiling point.

The correct name for the alkene shown here is _____ A) hexene B) 3-hexene C) cis-3-hexene D) trans-3-hexene E) methyl-3-pentene

The compound contains a six carbon chain with a double bond so it is a hexene. The double bond is in position 3 (counting from either end), and the ethyl groups attached to the double bonded carbons are on opposite (trans) sides of the double bond. So the name would be trans-3-hexene.

What is the IUPAC name for the compound shown here? A) trans-2-butene B) 2-butene C) cis-2-butene D) trans-butene E) cis-butene

The double bond position should be indicated in the name, and the methyl groups lie on the same side of the double bond, so the IUPAC name is cis-2-butene.

How many carbon atoms are present in benzene?

The formula of benzene is C₆H₆ therefore there are 6 carbon atoms

Determine the correct IUPAC name for the compound shown here

The longest chain is six carbons and there is a triple bond, so it is a hexyne. The triple bond is in the third position numbering from either name, so the name is 3-hexyne.

Which of the following fatty acids is predicted to have the highest melting point? A) CH₃(CH₂)₆COOH B) CH₃(CH₂)₈COOH C) CH₃(CH₂)₁₄COOH D) CH₃CH₂CH=CH(CH₂)₆COOH E) CH₃CH₂CH=CHCH=CHCOOH

The melting points of fatty acids increase with molecular weight, so the largest molecule, CH₃(CH₂)₁₄COOH, is predicted to have the highest melting point. The melting point of the saturated fatty acid is more than that of unsaturated fatty acid. The saturated fatty acid have more density and more number of hydrogen bonding. And these are clearly fit into the crystal. While the unsaturated acid due to the double not fits into their crystal neatly thus have low melting point. Saturated acid and contains no double bond thus have highest melting point .

Determine the expected molecular geometry for the indicated carbon in 2,4-dimethyl-3-hexene. A) linear B) trigonal planar C) tetrahedral D) bent E) trigonal pyramidal

This carbon atom is sp²-hybridized and thus the expected molecular geometry is trigonal planar.

Name the compound shown here. A) 3-pentylbenzene B) pentanebenzene C) 1-phenylpentane D) 2-phenylpentane E) 3-phenylpentane

This compound is more easily named as a derivative of the five carbon alkane pentane rather than as a derivative of benzene. A benzene radical is called a phenyl group, and it is attached to the three position of pentane, so it is named 3-phenylpentane.

Because compounds containing a double bond have fewer hydrogens than their corresponding alkanes, they are classified as: A) acyclic B) cyclic C) saturated D) unsaturated

Unsaturated The term unsaturated is used to classify hydrocarbons that contain at least one carbon-carbon double or triple bond.

Which of the following describes the type of hydrocarbon benzene is? A) aliphatic B) alkene C) alkyne D) alkane E) aromatic

aromatic

The product of the reaction between cyclopentane and chlorine in the presence of heat is A) chlorocyclopentane. B) cyclopentylchloride. C) cyclopentene. D) dicyclopentane. E) no reaction occurs.

chlorocyclopentane

Are the structures shown considered constitutional isomers, cis-trans isomers, the same molecule or are not related by isomerism? A) constitutional Isomers B) cis-trans isomers C) same molecule D) not related by isomerism

cis-trans isomers

The reaction of an alkane with oxygen to produce carbon dioxide and water is known as what? A) substitution B) displacement C) precipitation D) combustion E) double replacement

combustion

Classify α-cadinene, also known as citronella oil.

diene An alkene is a compound containing a carbon-carbon double bond. A diene is an alkene containing two carbon-carbon double bonds. A polyene is an alkene containing more than two carbon-carbon double bonds. α-cadinene is an alkene containing two carbon-carbon double bonds and would be classified as a diene.

Alkanes are generally soluble in what type of solvents?

nonpolar Recall "like dissolves like". Alkanes are essentially nonpolar compounds and would therefore be soluble in nonpolar solvents.

What are the possible major products of the reaction between benzene and 2 Br₂ in the presence of an iron catalyst? A) bromobenzene B) ortho- and para-dibromobenzene C) ortho- and meta-dibromobenzene D) meta- and para-dibromobenzene E) ortho-, meta- and para-dibromobenzene

ortho- and para-dibromobenzene Two bromines can be attached to benzene as two major possible arrangements: 1,2 (ortho) and 1,4 (para). Recall the a bromo-substituent is an ortho/para director.

Classify the reaction type of the following reaction. A) substitution B) elimination C) combustion D) isomerization

substitution

The polymer polyvinyl chloride (PVC) is composed of what monomer? A) vinyl B) chloride C) vinyl chloride D) ethylene E) propylene

vinyl chloride

What reagents are required to convert the alkene 1-propene to the alcohol 2-propanol? A) H₂ B) H₂O, H₂SO₄ C) Br₂ D) HBr

H₂O in the presence of an acid catalyst (ex. H₂SO₄) will add to the double bond of 1-propene, with H adding to C1 and OH adding to C2 to form 2-propanol

Determine the correct name for the cycloalkene shown here. A) dimethylcyclohexene B) 1,3-dimethylcyclohexene C) 1,4-dimethylcyclohexene D) 1,5-dimethylcyclohexene E) 1,3-dimethyl-2-cyclohexene

The compound contains six carbons in a ring, with a double bond in the ring and two methyl groups attached. The ring positions are numbered with the double bond positioned between carbons 1 and 2, with the direction of the numbering giving the lowest numbering for the two methyl substituents. Numbering the double bond position would therefore be redundant. So the name would be 1,3-dimethylcyclohexene.

How many hydrogen atoms are present in benzene?

The formula of benzene is C₆H₆ therefore there are 6 hydrogen atoms Benzene is the parent compound of the large family of organic compounds known as aromatic compounds. Unlike cyclohexane, benzene only contains six hydrogen atoms, giving the impression that the ring is unsaturated and each carbon atom participates in one double bond

Classify the reaction type for the following reaction: halogenation of benzene. A) combustion B) substitution C) elimination D) hydration E) hydrogenation

The halogenation of benzene is classified as an electrophilic substitution reaction because in this reaction benzene is attacked by an electrophile which results in the substitution of hydrogen with halogens. Combustion is the reaction in which a substance reacts with oxygen gas. Substitution is the reaction in which one atom, ion or group replaces by another atom. Elimination is the reaction in which a pair of atoms or groups are removed from the molecule. Hydration is the reaction in which water is added or combined into the substance. Hydrogenation is the reaction in which H2 is added or combined into the substance.

Name the structure below: A) 1-hexyne B) 2-ethynylbutane C) 2-ethyl-3-butyne D) 3-methyl-1-pentyne E) 3-methyl-4-pentyne

The longest chain is five carbons and there is a triple bond, so it is a pentyne. Number from the end that gives the lowest number to the triple bond, so the name is 3-methyl-1-pentyne.