Question

a. What do the terms saturated and unsaturated mean when applied to hydrocarbons? b. What other meanings do these terms have in chemistry? c. Classify alkenes, alkanes, alkynes, and aromatic hydrocarbons as either saturated or unsaturated.

Short answer

Saturated hydrocarbons have only single bonds; unsaturated contain double/triple bonds. Alkanes: saturated; Alkenes/Alkynes/Aromatics: unsaturated.

Step-by-step solution

Definitions of Saturated and Unsaturated Hydrocarbons

Saturated hydrocarbons are compounds that contain only single bonds between carbon atoms. Unsaturated hydrocarbons, on the other hand, contain one or more double or triple bonds.

Other Meanings in Chemistry

In chemistry, saturated means the solution contains the maximum amount of solute that can be dissolved at a given temperature. Unsaturated solutions can still dissolve more solute at the same temperature.

Classification of Hydrocarbons

Alkanes are saturated hydrocarbons because they contain only single bonds. Alkenes and alkynes are unsaturated hydrocarbons due to their double and triple bonds, respectively. Aromatic hydrocarbons are also considered unsaturated due to the delocalized electrons in their ring structure.

Key concepts

saturated hydrocarbons

Saturated hydrocarbons are organic compounds consisting exclusively of single bonds between carbon atoms. These are sometimes referred to as alkanes.
Examples include methane (CH₄), ethane (C₂H₆), and propane (C₃H₈).
The absence of double or triple bonds makes these compounds less reactive compared to unsaturated hydrocarbons.
The general formula for alkanes is CₙH₂ₙ₊₂. This formula helps to predict the structure of larger alkanes.

unsaturated hydrocarbons

Unsaturated hydrocarbons contain one or more double or triple bonds between carbon atoms, making them more chemically reactive.
These can be classified into alkenes (with one or more double bonds) and alkynes (with one or more triple bonds).
Another group includes aromatic hydrocarbons, which have delocalized electrons in a ring structure such as benzene.
These bonds cause the molecules to have fewer hydrogen atoms compared to alkanes.

alkanes

Alkanes are saturated hydrocarbons with only single bonds between carbon atoms.
As the simplest form of hydrocarbons, alkanes follow the general formula of CₙH₂ₙ₊₂.
They are less likely to participate in chemical reactions due to the stability of the single bonds.
Examples: Methane (CH₄), Ethane (C₂H₆), and Propane (C₃H₈).

alkenes

Alkenes are a type of unsaturated hydrocarbon that contain at least one double bond between carbon atoms.
This double bond makes alkenes more reactive than alkanes.
The general formula for alkenes is CₙH₂ₙ.
Examples: Ethene (C₂H₄), Propene (C₃H₆).

alkynes

Alkynes are unsaturated hydrocarbons that contain at least one triple bond between carbon atoms.
This triple bond gives alkynes even higher reactivity compared to alkenes and alkanes.
The general formula for alkynes is CₙH₂ₙ₋₂.
Examples: Ethyne (C₂H₂), Propyne (C₃H₄).

aromatic hydrocarbons

Aromatic hydrocarbons, also known as arenes, have a ring structure with delocalized electrons.
These rings create a unique, stable structure making them distinctive from other hydrocarbons.
Benzene (C₆H₆) is the simplest aromatic hydrocarbon.
Aromatics are unsaturated but have unique properties due to the resonance in their structures.

saturated solutions

A saturated solution is a solution that contains the maximum amount of solute that can be dissolved at a particular temperature.
No additional solute can dissolve into the solvent once it reaches this point.
Beyond this point, any added solute will remain undissolved.

unsaturated solutions

An unsaturated solution is one in which more solute can still be dissolved at the given temperature.
This indicates that the solution has not reached its maximum concentration of solute.
Such solutions can easily dissolve additional solute without forming any precipitate.