Alkanes and Cycloalkanes

These flashcards cover foundational concepts related to alkanes and cycloalkanes, including their structures, reactions, properties, and classifications.

What are the two main classes of hydrocarbons?

Aliphatic hydrocarbons and aromatic hydrocarbons.

What is the general molecular formula for alkanes?

CnH2n+2.

What are the three major types of aliphatic hydrocarbons?

Alkanes, alkenes, and alkynes.

What is the simplest alkane?

Methane (CH4).

What is the difference between n-butane and isobutane?

N-butane has a straight chain structure, while isobutane has a branched chain structure.

What is the estimated number of constitutional isomers for C5H12?

3.

What is the primary reason for the higher boiling points of unbranched alkanes compared to branched isomers?

Unbranched alkanes have a larger surface area for induced-dipole/induced-dipole interactions.

What is the effect of chain length on the boiling points of alkanes?

As the number of carbon atoms increases, the boiling point generally increases.

What does the term 'conformational analysis' refer to?

It refers to the study of different spatial arrangements of a molecule generated by rotation about single bonds.

What is the most stable conformation of cyclohexane?

The chair conformation.

What are the three types of van der Waals forces identified in the properties of alkanes?

Dipole–dipole, dipole/induced-dipole, and induced-dipole/induced-dipole.

What type of reaction do alkanes typically undergo when burned in air?

Combustion, producing carbon dioxide and water.

What is halogenation in the context of alkanes?

The substitution of a halogen atom for one of the alkane's hydrogens.

What is the significance of the 'magic acid' in the context of alkanes?

It facilitates protonation of hydrocarbons, which is a difficult process due to their low reactivity.

What are the two main operations involved in modern petroleum refining beyond distillation?

Cracking and reforming.

What is the bond dissociation energy for C-H bonds in alkanes?

Approximately 375 to 435 kJ/mol.

What is the impact of steric hindrance on the stability of axial substituents in cyclohexane?

Axial substituents experience crowding due to 1,3-diaxial interactions, making them less stable.

What is torsional strain in alkanes and cycloalkanes?

Strain that arises from eclipsed bonds when rotations occur around a carbon-carbon bond.

What is meant by regioselectivity in the halogenation of alkanes?

Certain hydrogen atoms in different positions of a hydrocarbon are abstracted with different probabilities, leading to a mix of products.

What is the exothermic reaction related to methane's combustion?

The release of energy when methane reacts with oxygen to produce carbon dioxide and water.