1000 Organic Chemistry Review Flashcards

This flashcard set contains 1000 Question and Answer pairs derived from organic chemistry multiple-choice questions, ranging from basic bonding to advanced polymer synthesis.

Which of the following is NOT a characteristic of organic compounds?

Bonds which bind the atoms together are nearly always ionic.

Which element is least likely to be found in an organic compound?

Silicon

What is one of the major sources of organic compounds?

Natural gas

What property of the carbon atom describes its ability to bond with other carbon atoms?

Catenation

In stable organic compounds, how many bonds does carbon always form?

$4$ bonds

What types of bonds consist of a carbon-carbon double bond?

one $\sigma$ bond, one $\pi$ bond

How many total bonds of each type does acetylene have?

three $\sigma$ bonds, two $\pi$ bonds

How many of each bond type are present in propene?

eight $\sigma$ bonds and one $\pi$ bond

How many of each bond type are present in propyne?

six $\sigma$ bonds and two $\pi$ bonds

What is the count of bond types in 1-Buten-3-yne?

seven $\sigma$ and three $\pi$ bonds

In which compound do carbons use only $sp^3$ hybrid orbitals for bond formation?

$$CH_3CH_2CH_3$$

Identify a compound in which carbon uses $sp^3$ hybrid orbitals for bond formation.

$$(CH_3)_3COH$$

When a carbon atom is $sp^2$ hybridized in a compound, to how many other atoms is it bonded?

$3$ other atoms

In which compound do carbons use only $sp^2$ hybrid orbitals for bond formation?

$$CH_2=CH-CH=CH_2$$

Which of the following is an example of a planar molecule?

Formaldehyde

What is the bond angle between the hybrid orbitals in methane?

$$109.5^\circ$$

What is the $H-C-C$ bond angle in ethane?

$$109.5^\circ$$

What is the $H-C-H$ bond angle in ethylene?

$$120^\circ$$

What is the bond length of a carbon-carbon double bond?

$$1.34\,\text{\AA}$$

Rank carbon-carbon bond lengths in order of increasing bond length.

triple, double, single

What is the correct order of bond lengths among single, double, and triple carbon-carbon bonds?

$$C\equiv C < C=C < C-C$$

Which of the following hydrocarbons has the shortest $C-C$ bond length?

$$HC \equiv CH$$

In which of these compounds is the carbon-carbon bond length maximum?

$$CH_3CH_3$$

What is the hybridization of the carbon atoms numbered 1 and 2 respectively in the provided structure?

$$sp^2, sp$$

How many atoms are attached to an atom having an $sp$ hybridization?

$$2$$

Which statement regarding resonance hybrids is true?

Resonance hybrids are averages of all resonance forms resembling the more stable forms.

What features do resonance structures of a molecule share?

same arrangement of atoms and same number of paired electrons

Which of the following types of compounds have planar molecules?

formaldehyde and 1,3-butadiene

Which of the following chloro-compounds will show a dipole moment?

cis-1,2-dichloroethylene and o-dichlorobenzene

Which molecule has a nonzero dipole moment?

$$CHCl_3$$

Which of the following compounds has the lowest dipole moment?

carbon tetrachloride

Which molecule has the greatest dipole moment among methyl halides?

$$CH_3F$$

Which of the following compounds has the highest dipole moment?

dichloromethane

Homolytic fission of a $C-C$ bond leads to the formation of which species?

Free radicals

What is the product of homolytic fission of a covalent bond between carbon atoms?

Free radicals

What is the order of stability for carbonium ions?

$$\text{tertiary} > \text{secondary} > \text{primary}$$

What is the order of stability for carbanions?

$$\text{primary} > \text{secondary} > \text{tertiary}$$

Which of the provided carbonium ions is the most stable?

Tertiary carbocation structure (d)

Which carbanion is considered the least stable?

Tertiary carbanion structure (b)

Which type of alkyl free radical is the most stable?

tertiary

Which of the following species is an electrophile?

Electrophile structure (b)

Which of the following is NOT an electrophile?

$$NH_3$$

What is a correct statement regarding nucleophiles?

They have a lone-pair of electrons.

Which of the following is a nucleophile?

$$CN^-$$

Which of the following is NOT a nucleophile?

$$AlCl_3$$

Identify which of the following is NOT a nucleophile.

$$BF_3$$

Which of the following is a Lewis acid?

$$AlCl_3$$

What range best represents the strength of a hydrogen bond?

$$5\text{--}10\,\text{kcals}$$

In terms of energy, how is bond strength or bond dissociation energy defined?

energy required to break a bond and energy released when a bond is formed

According to the transcript, when is energy released regarding chemical bonds?

Energy is released when a bond forms.

Which statement regarding resonance stabilization is incorrect?

Delocalized electrons destabilize a compound.

How should curved arrows be drawn in organic mechanism structures?

Curved arrows are always drawn from an electron rich center to an electron poor center.

What does a "curved" arrow represent in chemistry?

the movement of two electrons

What is the predicted shape, bond angle, and hybridization for $CH_3^+$?

trigonal planar, $120^\circ$, $sp^2$

What name is given to a species containing a positively charged carbon atom?

carbocation (also referred as methyl radical in transcript answer 55)

What orbitals overlap to create the $H-C$ bond in $CH_3^+$?

$$s\text{--}sp^2$$

The lone-pair electrons of the methyl anion occupy which type of orbital?

$$sp^3$$

An increase in which factor results in a decrease in the rate of a chemical reaction?

energy of activation

What is the name of the reaction step where the transition state is at the highest point?

rate-determining step

An electrophile acts as what when it reacts with a nucleophile?

Lewis acid

A nucleophile acts as what when it reacts with an electrophile?

Lewis base

Which of the following is not normally considered to be a nucleophile?

$$CH_3CH_2^+$$

Identify which of the following is NOT a nucleophile.

$$FeBr_3$$

Which of the following is the strongest interaction?

a covalent bond

Which statement regarding electron movement is incorrect?

An electron-rich atom is called an electrophile.

Which of the following is a nonpolar molecule?

$$H_2$$

Which species is defined as one that accepts a proton?

Bronsted-Lowry base

According to acid-base chemistry, what does a small $pK_a$ indicate?

a large $K_a$ and a stronger acid

What is the relationship between acid strength and its conjugate base?

The stronger the acid, the weaker its conjugate base.

What is the conjugate acid of $CH_3NH_2$?

$$CH_3NH_3^+$$

What is the conjugate base of $CH_3NH_2$?

$$CH_3NH^-$$

As acid strength increases, what happens to the stability of the conjugate base and the $pK_a$?

the conjugate base becomes more stable and the $pK_a$ becomes smaller (Note: Corrected context for Transcript answer 72: the weaker its conjugate base).

Which of the following is the strongest acid?

$$HI$$

Which of the following are examples of Lewis bases?

$NF_3$ and $CH_3OCH_3$

What terms describe compounds with the same atoms attached to the same atoms but different orientations in space?

Stereoisomers

What must isomers of a substance always share?

same molecular weight

What are compounds with the same molecular formula but different structural formulas called?

Isomers

Ethanol and dimethyl ether are classified as what type of isomers?

structural isomers

The compounds $CH_3CH_2OCH_2CH_3$ and $CH_3OCH_2CH_2CH_3$ are examples of what?

Metamers

Which statement is false regarding tautomers?

Tautomers have independent existence.

How many isomers are possible for the compound with molecular formula $C_4H_8$?

$$6$$

How many structural isomers are possible for $C_4H_9Br$?

$$4$$

How many isomeric aromatic hydrocarbons are possible for $C_8H_{10}$?

$$4$$

Which of the following is NOT an isomer of n-Pentane, 2,2-Dimethylpropane, and 2-Methylbutane?

2,3-Dimethylbutane

Why do alkenes exhibit geometrical isomerism?

Restricted rotation around a double bond

Which of the following compounds exhibits geometrical isomerism?

2-Pentene

Which of the following compounds exist as cis-trans isomers?

2-Butene

Which acid is known to show geometrical isomerism?

Maleic acid

Which of the following dimethyl compounds shows geometrical isomerism?

$$CH_3CH=CHCH_3$$

Which compound with chlorine and bromine shows geometrical isomerism?

$$ClCH=CHBr$$

Identify which compound does NOT show geometrical isomerism.

Structure (d) (Note: Cycloalkene with specific substituents in transcript)

When is a molecule said to be chiral?

if it cannot be superimposed on its mirror image

Which statement is false regarding chiral compounds?

they have cis and trans isomers

By definition, an optically active compound in solution will do what?

rotate the plane of polarized light

What type of light is affected by chiral molecules?

Plane-polarized light

How can one distinguish between optical isomers?

by polarimetry

What are optical isomers that are mirror images called?

Enantiomers

What are optical isomers that are NOT mirror images called?

Diastereomers

Which characteristic is true of enantiomers?

they have the same melting point

Which statement is false about enantiomers?

they are superimposable mirror images