Exploring Organic Chemistry: Hydrocarbons, Functional Groups, and Polymers

Introduction to Organic Chemistry

Organic chemistry is the study of carbon-based compounds, which make up a vast array of molecules found in living organisms and many materials around us. This branch of chemistry is crucial in understanding the properties and reactions of hydrocarbons, functional groups, and polymers.

Hydrocarbons

Hydrocarbons are compounds composed solely of carbon and hydrogen atoms. They can be classified into two main categories:

• Alkanes: Saturated hydrocarbons with only single bonds between carbon atoms. Examples include methane (CH4), ethane (C2H6), and propane (C3H8).
• Alkenes: Unsaturated hydrocarbons with at least one carbon-carbon double bond. Examples include ethene (C2H4) and propene (C3H6).

Crude Oil and Fractional Distillation

Crude oil, a complex mixture of hydrocarbons, is formed from the decomposition of ancient marine organisms over millions of years. Through fractional distillation, crude oil is separated into various fractions based on their boiling points, such as:

• Refinery gases (e.g., methane, ethane)
• Petrol (gasoline)
• Kerosene
• Diesel fuel
• Lubricating oils
• Bitumen (used for road surfaces)

Alkenes and Polymerization

Alkenes exhibit characteristic reactions, such as the addition of bromine water, which can help identify their presence. Furthermore, alkenes can undergo polymerization, a process in which monomers (small molecules) join together to form long-chain polymers. This reaction is crucial in the production of plastics like poly(ethene) and poly(propene).

Functional Groups

Functional groups are specific atom arrangements within organic molecules that determine their properties and reactivity. Two important functional groups are:

• Alcohols: Contain the -OH group and exhibit properties like solubility in water and combustibility. Examples include methanol (CH3OH) and ethanol (C2H5OH).
• Carboxylic acids: Contain the -COOH group and exhibit properties like acidity and reactivity with bases. Examples include methanoic acid (HCOOH) and ethanoic acid (CH3COOH).

Worked Example: Identifying Alkenes

Problem: A hydrocarbon compound reacts with bromine water, causing the solution to turn from orange to colorless. What type of hydrocarbon is it, and what does this reaction indicate?

Solution:

• The reaction with bromine water turning colorless indicates the presence of a carbon-carbon double bond.
• Hydrocarbons with double bonds are classified as alkenes.
• Therefore, the given compound is an alkene.