O CHEM CHAPTER 1 and 2

A polar covalent bond is one in which electrons are _____________.

not shared equally

Unsaturated hydrocarbons may be distinguished from saturated hydrocarbons by the presence of one or more _____________.

pi bonds

Draw all isomers of C3H8O and classify each according to functional group

primary alcohol, secondary alcohol and ether

When the ls orbitals of two hydrogen atoms combine to form a hydrogen molecule, which molecular orbitals are formed? A) One bonding molecular orbital only B) Two bonding molecular orbitals C) One bonding molecular orbital and one antibonding molecular orbital D) Two antibonding molecular orbitals E) Three bonding molecular orbitals

C

Which compound has the shortest carbon-carbon bond(s)? A) CH3CH3 B) CH2=CH2 C) HC≡CH D) CH3CH2CH3 E) All carbon-carbon bonds are the same length.

C

Which compound would you expect to have the highest boiling point? A) CH3OCH2CH2OCH3 B) CH3OCH2OCH2CH3 C) HOCH2CH2CH2CH2OH D) CH3OCH2CH2CH2OH E) (CH3O)2CHCH3

C

Which of these substances contains both covalent and ionic bonds? A) NH4Cl B) H2O2 C) CH4 D) HCN E) H2S

A

. When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how many molecular orbitals are formed? A) 1 B) 2 C) 3 D) 4 E) 5

B

According to molecular orbital theory, in the case of a carbon-carbon double bond, the carbon-carbon bonding electrons of higher energy occupy this molecular orbital. A) σ bonding MO B) π bonding MO C) σ* antibonding MO D) π* antibonding MO E) π* bonding MO

B

According to molecular orbital theory, which molecule could not exist? A) H2 B) He2 C) Li2 D) F2 E) N2

B

An oxygen-containing compound shows strong IR absorption at 1630-1780 cm-1 and 3200-3550 cm-1. What type of compound is it likely to be? A) An alcohol B) A carboxylic acid C) An ether D) A ketone E) An aldehyde

B

An oxygen-containing compound which shows sharp IR absorption at 2200 cm-1 and 3300 cm-1 is likely to be what type of compound? A) An ester B) An alkene C) An alkyne D) An ether E) An aldehyde

B

For a molecule to possess a dipole moment, the following condition is necessary but not sufficient. A) Three or more atoms in the molecule B) Presence of one or more polar bonds C) A non-linear structure D) Presence of oxygen or fluorine E) Absence of a carbon-carbon double or triple bond

B

How many 2p atomic orbitals from boron must be mixed with a 2s atomic orbital to yield the bonding hybrid atomic orbitals in BF3? A) 1 B) 2 C) 3 D) 4 E) 5

B

Draw all isomers of C6H12O that are aldehydes and contain at least one tertiary carbon

4

Draw all the isomers of C4H9Br, using bond-line formulas

4

Draw all isomers of C6H14.

5

Draw all isomers of C4H8, using bond-line formulas

6

Draw all tertiary amine isomers of C6H15N.

6

Draw all isomers of C6H12O that are aldehydes.

7

Draw all the isomers of C4H10O, using bond-line formulas

7

The IR spectrum of which type of compound will not show evidence of hydrogen bonding? A) Aldehyde B) Alcohol C) Carboxylic acid D) Phenol E) Primary amine

A

The IR stretching frequency can be predicted to occur at the highest frequency for which of these bonds? A) C-H B) C-F C) C-Cl D) C-Br

A

The solid alkane CH3(CH2)18CH3 is expected to exhibit the greatest solubility in which of the following solvents? A) CCl4 B) CH3OH C) H2O D) CH3NH2 E) HOCH2CH2OH

A

When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how are the electrons distributed in the resulting molecular orbitals? A) 2 electrons in the bonding molecular orbital B) 1 electron in the bonding molecular orbital, 1 electron in the non-bonding molecular orbital C) 1 electron in the bonding molecular orbital, 1 electron in the antibonding molecular orbital D) 2 electrons in the non-bonding molecular orbital E) 2 electrons in the antibonding molecular orbital

A

The IR stretching frequency occurs at the lowest frequency for which of these bonds? A) C-H B) C-O C) C-Br D) C-N E) C-F

C

The absorption band for the O-H stretch in the IR spectrum of an alcohol is sharp and narrow in the case of: A) a Nujol mull of the alcohol. B) a concentrated solution of the alcohol. C) a gas phase spectrum of the alcohol. D) the spectrum of the neat liquid E) none of these

C

The IR spectrum of which type of compound generally exhibits evidence of hydrogen bonding? A) Aldehyde B) Carboxylic acid C) Alkene D) Ester E) Ketone

B

The greatest degree of ionic character is anticipated for the bond between: A) H and C B) H and Cl C) C and Cl D) H and Br E) Br and Cl

B

What bond angle is associated with a tetrahedral molecule? A) 120° B) 109.5° C) 180° D) 90° E) 45°

B

What is the empirical formula for cyclohexane? (Its molecular formula is C6H12.) A) CH B) CH2 C) C2H4 D) C6H6 E) C2H2

B

What would be the spatial arrangement of the atoms of the ozone molecule (O3)? A) Linear B) Angular C) Trigonal planar D) Trigonal pyramidal E) Tetrahedral

B

Which molecule has a non-linear structure (i.e., for which molecule are the nuclei not in a straight line)? A) O=C=O B) H-O-H C) H-Cl D) H-C≡N E) H-C≡C-H

B

Which molecule has a zero dipole moment? A) SO2 B) CO2 C) CO D) CHCl3 E) None of these

B

Which molecule would be linear? (In each case you should write a Lewis structure before deciding.) A) SO2 B) HCN C) H2O2 D) H2S E) OF2

B

Which of the following species exhibits resonance stabilization? A) H2SO4 B) O3 C) CO2 D) CCl4 E) None of the above species exhibit resonance

B

Which of these is the weakest of the intermolecular attractive forces? A) Ion-ion B) van der Waals C) Dipole-dipole D) Covalent bonding E) Hydrogen bonding

B

The bond angles in PH3 would be expected to be approximately: A) 60° B) 90° C) 105° D) 109° E) 120°

C

The following electron configuration represents _______. !!1s !!2sp3 !2sp3 !2sp3 !2sp3 A) the ground state of boron. B) the sp3 hybridized state of carbon. C) the sp3 hybridized state of nitrogen. D) the ground state of carbon. E) an excited state of carbon.

C

The number of unique open-chain structures corresponding to the molecular formula C3H5Cl is: A) 2 B) 3 C) 4 D) 5 E) 6

C

VSEPR theory predicts an identical shape for all of the following, except: A) NH3 B) H3O+ C) BH3 D) CH3 - E) All have the same geometry

C

What is the approximate hybridization state of the oxygen molecule in ethanol, C2H5OH? A) sp B) sp2 C) sp3 D) p3 E) d2sp3

C

What is the approximate hybridization state of the oxygen molecule in trimethylamine, (CH3)3N? A) sp B) sp2 C) sp3 D) p3 E) d2sp3

C

What shape does the methyl cation, CH3+, have? A) Octahedral B) Tetrahedral C) Trigonal planar D) Linear E) Trigonal pyramidal

C

Which of these would you expect to have the lowest boiling point? A) CH3CH2CH2OH B) CH3CHCH3 OH C) CH3OCH2CH3 D) CH3CH2CH2CH2OH E) CH3CH2OCH2CH3

C

Credit for the first synthesis of an organic compound from an inorganic precursor is usually given to: A) Berzelius B) Arrhenius C) Kekule D) Wohler E) Lewis

D

ExpAns:ion of the valence shell to accommodate more than eight electrons is possible with: A) Fluorine B) Nitrogen C) Carbon D) Sulfur E) Beryllium

D

In which molecule is the central atom sp3 hybridized? A) CH4 B) NH3 C) H2O D) All of these E) None of these

D

In which molecule(s) can the molecular geometry be attributed to an sp2 hybridized central atom? A) PBr3 B) CH4 C) CHCl3 D) HNO2 E) None of the above has an sp2 hybridized central atom

D

In which of the following would you expect the central atom to be sp3 hybridized (or approximately sp3 hybridized)? A) BH4- B) NH4+ C) CCl4 D) CH3:- E) All of these

D

Of the following compounds, the one with the highest boiling point is: A) CH3CH3 B) CH3CH2Cl C) CH3C=O H D) CH3CH2OH E) CH3CH2OCH2CH3

D

The IR stretching frequency can be expected to occur at the lowest frequency for which of these bonds? A) C-H B) O-H C) N-H D) S-H E) Difficult to predict

D

The IR stretching frequency occurs at the lowest frequency for which of these bonds? A) B-H B) O-H C) N-H D) S-H E) Difficult to predict

D

The strongest of attractive forces is which type? A) van der Waals B) Ion-dipole C) Dipole-dipole D) Cation-anion E) Hydrogen bonds

D

Which molecule has a zero dipole moment? A) CH3Cl B) CH2Cl2 C) CHCl3 D) CCl4 E) None of these

D

Which molecule would have a dipole moment greater than zero? A) BeCl2 B) BCl3 C) CO2 D) H2O E) CCl4

D

Which of the following contains an sp2 -hybridized carbon? A) CH4 B) CH3:− C) CH3CH3 D) CH3+ E) HC≡CH

D

Which of the following is not found in the following substance? CH3CH2CH2CH2CH2OH A) Ion-ion B) van der Waals C) Dipole-dipole D) Resonance E) Hydrogen bonding

D

Which of these structures would be a perfectly regular tetrahedron? A) CH3Br B) CH2Br2 C) CHBr3 D) CBr4 E) More than one of these

D

How many sigma (1s-2sp3 ) bonds are there in ethane? A) 7 B) 6 C) 5 D) 3 E) 1

B

1. In quantum mechanics a node (nodal surface or plane) is: A) a place where Ψ is negative. B) a place where Ψ is positive. C) a place where Ψ = 0. D) a place where Ψ2 is large. E) a place where Ψ2 is negative.

C

There are three fundamental rules that we use in writing electronic configurations for atoms and molecules. The configuration shown below (for oxygen) violates one of these rules. Which one? !!1s !!2s !!2p !2p !2p

Pauli Exclusion

Sodium chloride, which is quite soluble in water, is not very soluble in hexane. Why?

Sodium chloride, which is an ionic substance, is soluble in a polar solvent such as water, but not in a non-polar solvent such as hexane.

Define an orbital.

a region of space where the probability of finding an electron is high

An orbital is defined as a region of space where the probability of _________________ is high.

finding an electron

Organic compounds are classified into chemical families on the basis of similarities in chemical properties; these similarities are primarily due to the presence of characteristic arrangements of atoms known as ________________.

functional groups

Different compounds with the same molecular formula are referred to as __________.

isomers

When atomic orbitals of the same phase overlap a(n) _________________ molecular orbital is formed.

bonding

Select the most electronegative element. A) H B) O C) N D) B E) C

C

The C-O-C bond angle in diethyl ether is predicted to be approximately: A) 90º B) 105º C) 110º D) 120º E) 180º

C

Based on the VSEPR theory, which of the following would have a tetrahedral arrangement of electrons around the central atom? A) BH3 B) NO2 − C) SiH4 D) CO3 2− E) SO3

C

Cis-trAns: isomerism is possible only in the case of: A) CH2=CBr2 B) CH2=CHBr C) BrCH=CHBr D) Br2C=CHBr E) Br2C=CBr2

C

Considering Lewis structures, which of these compounds possesses a single unpaired electron? A) N2 B) N2O C) NO D) N2O4 E) O2

C

How many 2º alkyl bromides, neglecting stereoisomers, exist with the formula C6H13Br? A) 4 B) 5 C) 6 D) 7 E) 8

C

How many resonance structures can be written for the NO3 - ion in which the nitrogen atom bears a formal charge of +1? A) 1 B) 2 C) 3 D) 4 E) 5

C

Identify the atomic orbitals in the C-C sigma bond in ethyne. A) (2sp2, 2sp2) B) (2sp3, 2sp3) C) (2sp, 2sp) D) (2p, 2p) E) (2sp, 1s)

C

In which of the following does the central atom have 2 pairs of non-bonding electrons? A) O3 B) CO2 C) CO32− D) NH4+ E) H2S

C

Which of these compounds would have the highest boiling point? A) CH3OCH2CH2CH2OCH3 B) CH3CH2OCH2CH2OCH3 C) CH3CH2OCH2OCH2CH3 D) CH3OCH2CHOCH3 CH3 E) HOCH2CH2CH2CH2CH2OH

E

Which principle(s) or rule must be used to determine the correct electronic configuration for carbon in its ground state? A) Aufbau Principle B) Hund's Rule C) Pauli Exclusion Principle D) (A) and (B) only E) All three

E

A compound consists only of carbon, hydrogen and oxygen. Elemental analysis gave: C, 70.5%, H, 13.8%. The molecular weight of the compound was found to be 103 +/- 3. What is the molecular formula for the compound? A) C6H12O B) C5H12O2 C) C3H2O4 D) C3H6O3 E) C6H14O

E

An anticipated IR absorption band may not be observed because: A) it occurs outside the range of the instrument used. B) no change occurs in the dipole moment during the vibration. C) the absorption band is eclipsed by another. D) the intensity is so weak that it cannot be differentiated from instrument noise. E) All of these

E

Based on VSEPR theory, which of the following would have a trigonal planar shape? A) CH3)3N B) HCN C) NH4+ D) CH3− E) CH3+

E

CH3CH2OCH2CH3 and CH3CH2CH2CH2OH are examples of what are now termed: A) Structural isomers B) Resonance structures C) Functional isomers D) Empirical isomers E) Constitutional isomers

E

How many constitutional isomers are possible with the formula C4H10O? A) 3 B) 4 C) 5 D) 6 E) 7

E

Select the least electronegative element A) P B) N C) Mg D) Si E) K

E

What would be the spatial arrangement of the atoms of the methyl anion, :CH3 - ? A) Octahedral B) Tetrahedral C) Trigonal planar D) Linear E) Trigonal pyramidal

E

Which of the following would have no net dipole moment (P = 0 D)? A) CBr4 B) cis-1,2-Dibromoethene C) trAns:-1,2-Dibromoethene D) 1,1-Dibromoethene E) More than one of these

E

The IR absorption frequencies of the C-H bond in alkanes, alkenes and alkynes are measurably different. Briefly explain why.

IR absorption frequency depends on bond strength; the bond strength of C-H bonds in alkanes, alkenes and alkynes is different because different atomic orbitals (hybridized) of carbon are involved in the bond: the C-H bond in alkanes is described as (sp3-s), that in alkenes is (sp2-s) and in alkynes, it is (sp-s). The relative % s v. % p character of the hybrid orbitals of carbon would indicate different bond lengths /bond strengths for alkanes, alkenes and alkynes, with the bond length / bond strength being the longest/weakest respectively. This results in different IR absorption frequencies.

Hydrocarbons containing carbon-carbon double bonds are referred to as ___________.

alkenes

When atomic orbitals of opposite phase overlap a(n) _________________ molecular orbital is formed.

antibonding

A group in which a carbon atom has a double bond to an oxygen atom is called a __________.

carbonyl

Constitutional isomers differ in the _________________.

connectivity of their atoms

The bond that results when two atoms share a pair of electrons is called a _________________.

covalent bond

The six p-electrons in benzene are _____________ about the ring, which explains why all of the C-C bonds are the same length.

delocalized

Organic compounds were originally defined as compounds obtained from __________.

living sources/organisms

The modern definition of organic chemistry is _________________.

study of carbon compounds