Key Terms, Key Equations, and Exercises (Chapter 21)

Write the chemical formula and Lewis structure of the following, each of which contains five carbon atoms:

(a) an alkane

(b) an alkene

(c) an alkyne

On a microscopic level, how does the reaction of bromine with a saturated hydrocarbon differ from its reaction with an unsaturated hydrocarbon? How are they similar?

Explain why unbranched alkenes can form geometric isomers while unbranched alkanes cannot. Does this explanation involve the macroscopic domain or the microscopic domain?

Explain why these two molecules are not isomers:

Write the Lewis structure and molecular formula for each of the following hydrocarbons:

(a) hexane

(b) 3-methylpentane

(c) cis-3-hexene

(d) 4-methyl-1-pentene

(e) 3-hexyne

(f) 4-methyl-2-pentyne

Give the complete IUPAC name for each of the following compounds:

(a) CH₃CH₂CBr₂CH₃

(b) (CH₃)₃CCl

(c)

(d) CH3CH2C≡CH CH3CH2C≡CH${\text{CH}}_3{\text{CH}}_2\text{C}\equiv {\text{CH CH}}_3{\text{CH}}_2\text{C}\equiv \text{CH}$

(e)

(f)

(g) (CH3)2CHCH2CH=CH2${\left({\text{CH}}_3\right)}_2{\text{CHCH}}_2\text{CH}={\text{CH}}_2$

Butane is used as a fuel in disposable lighters. Write the Lewis structure for each isomer of butane.

Write Lewis structures for the cis–trans isomers of CH3CH=CHCl.${\text{CH}}_3\text{CH}=\text{CHCl.}$

Isooctane is the common name of the isomer of C₈H₁₈ used as the standard of 100 for the gasoline octane rating:

(a) What is the IUPAC name for the compound?

(b) Name the other isomers that contain a five-carbon chain with three methyl substituents.

Write Lewis structures and IUPAC names for all isomers of C₄H₉Cl.

Write the structures for all the isomers of the –C₅H₁₁ alkyl group.

Benzene is one of the compounds used as an octane enhancer in unleaded gasoline. It is manufactured by the catalytic conversion of acetylene to benzene:
3C2H2⟶C6H6$3{\text{C}}_2{\text{H}}_2⟶{\text{C}}_6{\text{H}}_6$

Draw Lewis structures for these compounds, with resonance structures as appropriate, and determine the hybridization of the carbon atoms in each.

Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.

(a) 1 mol of 1-butyne reacts with 2 mol of iodine.

(b) Pentane is burned in air.

What mass of 2-bromopropane could be prepared from 25.5 g of propene? Assume a 100% yield of product.

Ethylene can be produced by the pyrolysis of ethane:
C2H6⟶C2H4+H2${\text{C}}_2{\text{H}}_6⟶{\text{C}}_2{\text{H}}_4+{\text{H}}_2$

How many kilograms of ethylene is produced by the pyrolysis of 1.000 ×$\times$ 10³ kg of ethane, assuming a 100.0% yield?

Write condensed formulas and provide IUPAC names for the following compounds:

(a) ethyl alcohol (in beverages)

(b) methyl alcohol (used as a solvent, for example, in shellac)

(c) ethylene glycol (antifreeze)

(d) isopropyl alcohol (used in rubbing alcohol)

(e) glycerine

Give the complete IUPAC name and the common name for each of the following compounds:

(a)

(b)

(c)

Write the condensed structures of all isomers with the formula C₂H₆O₂. Label the functional group (or groups) of each isomer.

MTBE, Methyl tert-butyl ether, CH₃OC(CH₃)₃, is used as an oxygen source in oxygenated gasolines. MTBE is manufactured by reacting 2-methylpropene with methanol.

(a) Using Lewis structures, write the chemical equation representing the reaction.

(b) What volume of methanol, density 0.7915 g/mL, is required to produce exactly 1000 kg of MTBE, assuming a 100% yield?

Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.

(a) 2-butene is treated with water in dilute acid

(b) ethanol is dehydrated to yield ethene

Predict the products of oxidizing the molecules shown in this problem. In each case, identify the product that will result from the minimal increase in oxidation state for the highlighted carbon atom:

(a)

(b)

(c)

Explain why it is not possible to prepare a ketone that contains only two carbon atoms.

Fatty acids are carboxylic acids that have long hydrocarbon chains attached to a carboxylate group. How does a saturated fatty acid differ from an unsaturated fatty acid? How are they similar?

Write a condensed structural formula, such as CH₃CH₃, and describe the molecular geometry at each carbon atom.

(a) 2-propanol

(b) acetone

(c) dimethyl ether

(d) acetic acid

(e) 3-methyl-1-hexene

Write the two-resonance structures for the acetate ion.

Write two complete balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.

(a) 1-butanol reacts with acetic acid

(b) propionic acid is poured onto solid calcium carbonate

Alcohols A, B, and C all have the composition C₄H₁₀O. Molecules of alcohol A contain a branched carbon chain and can be oxidized to an aldehyde; molecules of alcohol B contain a linear carbon chain and can be oxidized to a ketone; and molecules of alcohol C can be oxidized to neither an aldehyde nor a ketone. Write the Lewis structures of these molecules.

What is the molecular structure about the nitrogen atom in trimethyl amine and in the trimethyl ammonium ion, (CH₃)₃NH⁺? What is the hybridization of the nitrogen atom in trimethyl amine and in the trimethyl ammonium ion?

Draw Lewis structures for pyridine and its conjugate acid, the pyridinium ion, C₅H₅NH⁺. What are the geometries and hybridizations about the nitrogen atoms in pyridine and in the pyridinium ion?

Write two complete balanced equations for the following reaction, one using condensed formulas and one using Lewis structures.

Methyl amine is added to a solution of HCl.

Identify any carbon atoms that change hybridization and the change in hybridization during the reactions in Exercise 21.26.

Identify any carbon atoms that change hybridization and the change in hybridization during the reactions in Exercise 21.51.