Organic Chemistry : Organic Concepts

Study concepts, example questions & explanations for Organic Chemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #131 : Organic Concepts

Which of these is a tertiary amine?

Possible Answers:

Aniline

Trimethylamine

None of the other answers

Piperidine

Ammonia

Correct answer:

Trimethylamine

Explanation:

A tertiary amine has three organic groups bonded to it. Triethylamine has three ethyl groups bonded to it, so that is the correct answer. Ammonia is so it has no organic groups attached. Piperidine is a six-membered ring with a nitrogen as one of the members, making it a secondary amine. Aniline is a benzene ring with a  bonded to it, so it is a primary amine.

Example Question #41 : Organic Functional Groups

Which of the following molecules is an amine?

A)

Aldehyde

B)

Amide

C)

Amine

D)

Carboxylic acid

Possible Answers:

B

None of these

A

D

C

Correct answer:

C

Explanation:

C is the correct answer.

Amine

The molecule pictured above is an anime because it contains a nitrogen group bonded to two hydrogen atoms and one R-group. A shows an aldehyde, B shows an amide, and D shows a carboxylic acid.

Example Question #1 : Identifying Amino Compounds

Which of the following is the most accurate characteristic of ammonia?

Possible Answers:

It is a Lewis acid

It is a Lewis base

It has two lone pairs of electrons

It is an electrophile

Correct answer:

It is a Lewis base

Explanation:

For this question, we're being asked to identify a characteristic of ammonia.

First, we need to remember what ammonia is. Ammonia is a molecule that consists of a nitrogen atom bonded to three separate hydrogen atoms. In doing so, these three bonds contribute to six of the valence shell electrons for nitrogen. The remaining two valence electrons exists on the nitrogen atom as a lone pair. Thus, there is only one lone pair of electrons (pair being two).

Also, the lone pair of electrons on ammonia allows it to act as a Lewis base by donating them (not a Lewis acid, which accepts electrons). Furthermore, this tendency for ammonia to donate its electrons would make it a nucleophile, not an electrophile.

Example Question #41 : Organic Functional Groups And Molecules

The molecule guanosine, as shown below, is an important nucleoside found in biological systems. When combined with phosphate groups, guanosine acts as a vital constituent of nucleic acids. Based on the structure of this compound, how many amide groups are there in this molecule?

 Guanosine

Possible Answers:

Correct answer:

Explanation:

In this question, we're shown the structure of the nucleoside called guanosine. We're asked to determine how many amide functional groups exist in this molecule.

First, to answer this question, we need to know what an amide functional group is. Amides consist of a carbon atom double bonded to an oxygen atom, and single bonded to a nitrogen atom. Note that this is distinct from the similarly named amine functional group, which contains a nitrogen atom with a lone pair of electrons and single bonded to three other atoms, which can be hydrogen or "R-groups" containing carbon atoms.

When looking at the molecular structure of guanosine, we can see that there is only a single amide group.

Guanosine answer

Example Question #43 : Organic Functional Groups

What is the IUPAC name for the compound shown?

Img 1326

Possible Answers:

propanamine

1-aminopropane

1-propanamine

3-propanamine

Correct answer:

1-propanamine

Explanation:

The molecule's longest carbon chain has 3 carbons (thus, "prop"), and the lack of double bonds makes it an alkANe (thus "propan-"). The only functional group on this molecule is the amino group (thus "propanamine"), located on carbon number 1 if read from right to left, or carbon number 3 if read from left to right. The IUPAC rules state that the correct name for a molecule numbers the carbon chain such that functional groups get the lowest numbers possible. Thus "1-propanamine."

Example Question #1 : Identifying Other Organic Compounds

Img 0601

How many conjugated atoms are present in the given molecule?

Possible Answers:

Correct answer:

Explanation:

A conjugated molecule is one that has its atoms arranged in such a way that allows p orbitals to lie parallel to each other. This allows for electron delocalization, which ultimately provides increased stability for the molecule. To find conjugated atoms, look for alternating single and multiple bonds. The circled carbon atoms are the only ones that are conjugated in this molecule.

Img 0604

Example Question #2 : Identifying Other Organic Compounds

Img 0601

How many hydrogens are present in the given molecule?

Possible Answers:

Correct answer:

Explanation:

Each alcohol group provides a hydrogen. Additionally, there are 24 "hidden" hydrogens. Refer to the photo below to see where these "hidden" hydrogens are located.

Img 0610

Example Question #43 : Organic Functional Groups And Molecules

Img 0600

What type of orbital is the lone pair on the nitrogen found in?

Possible Answers:

sp3

p

sp

sp2

Correct answer:

sp2

Explanation:

In this molecule, the carbon that is directly attached to the nitrogen and the nitrogen itself are sp2 hybridized. This means that, within this bond, there are three sp2 orbitals present and the lone pair on the nitrogen occupies one of them.

Example Question #4 : Identifying Other Organic Compounds

What is the general formula of an ether?

Possible Answers:

Correct answer:

Explanation:

 is the general formula of an ether.

Example Question #5 : Identifying Other Organic Compounds

List all functional groups in the given molecule.

Possible Answers:

Ether, carboxylic acid, alkyl halide

Ester, carboxylic acid, alkyl halide, methyl

Ether, alcohol, Acid anhydride, ketone

Ester, alcohol, ketone

Correct answer:

Ether, carboxylic acid, alkyl halide

Explanation:

The first carbon that is attached to the chlorine is an alkyl halide. The oxygen that is directly attached to two carbons is an ether. Lastly, the  is a carboxylic acid.

Learning Tools by Varsity Tutors