Question

Natural gas consists of chiefly methane, but also contains ethane, propane, butane and isobutene. Which of the following compounds is NOT found in natural gas? A. sec-butane B. 2-methylbutane C. olefin \(\left(\mathrm{CH}_2 \mathrm{CH}_2\right)\) D. cyclopropane

Short answer

Option D (cyclopropane) is not found in natural gas.

Step-by-step solution

- Understand the components of natural gas

Natural gas primarily consists of methane \(\text{CH}_4\), but also contains other hydrocarbons such as ethane \(\text{C}_2\text{H}_6\), propane \(\text{C}_3\text{H}_8\), butane \(\text{C}_4\text{H}_{10}\), and isobutane \(\text{C}_4\text{H}_{10}\).

- Identify the given compounds

From the given options, identify the chemical formula and structure of each compound: A. sec-butane \(\text{C}_4\text{H}_{10}\) B. 2-methylbutane \(\text{C}_5\text{H}_{12}\) C. olefin \(\text{CH}_2\text{CH}_2\) D. cyclopropane \(\text{C}_3\text{H}_6\)

- Compare each compound to natural gas components

Compare each of the compounds from the options to the known components of natural gas: A. sec-butane is a form of butane, which is present in natural gas. B. 2-methylbutane (also known as isopentane) is not typically found in natural gas. C. olefin (ethylene) \(\text{CH}_2\text{CH}_2\) is an unsaturated hydrocarbon, generally not found in natural gas. D. cyclopropane is not typically found in natural gas.

- Conclude the compound not found in natural gas

From the comparison, both olefin (ethylene) and cyclopropane are not commonly found in natural gas. However, cyclopropane is less likely to appear in the context of natural gas than ethylene.

Key concepts

hydrocarbons

Hydrocarbons are compounds made up solely of hydrogen and carbon atoms. They are the building blocks of many organic substances and can be found in various forms such as gases, liquids, and solids. In the context of natural gas, hydrocarbons play a significant role. The most common hydrocarbons in natural gas include methane, ethane, propane, butane, and isobutane. These are essential energy resources and are used in heating, electricity generation, and as raw materials in the chemical industry. There are two main types of hydrocarbons:

• **Alkanes**: Saturated hydrocarbons with single bonds, such as methane, ethane, and propane.
• **Alkenes**: Unsaturated hydrocarbons with at least one double bond, like ethylene (an options in the original problem).

Saturated hydrocarbons like those found in natural gas are generally more stable and are key components of fossil fuels.
Understanding the different types of hydrocarbons helps in recognizing their various applications and importance in both natural and industrial processes.

organic chemistry

Organic chemistry is the branch of chemistry that focuses on the study of carbon-containing compounds. This includes understanding the structure, properties, composition, reactions, and synthesis of organic molecules, which are the fundamental elements of life. Organic chemistry covers a wide array of substances that include not only hydrocarbons but also their derivatives. In this exercise, we see an application of organic chemistry in identifying the components of natural gas:

• **Methane \(\text{CH}_4\)**: The simplest alkane and primary component of natural gas. Highly combustible and a significant source of energy.
• **Ethane \(\text{C}_2\text{H}_6\)**: Another alkane, used predominantly in the production of ethylene for the chemical industry.
• **Propane \(\text{C}_3\text{H}_8\)**: Used as a fuel for heating and engines, commonly found in LPG (liquefied petroleum gas).
• **Butane \(\text{C}_4\text{H}_{10}\)** and **Isobutane \(\text{C}_4\text{H}_{10}\)**: Often used as a fuel in lighters and portable stoves.

The goal of organic chemistry is to delve deeper into how these compounds interact, their practical applications, and their importance in our daily lives. A basic understanding aids in solving problems like identifying the presence of certain compounds in natural gas.

methane, ethane, propane, butane, isobutane

Each of these compounds is a hydrocarbon and an important component of natural gas:

• **Methane \(\text{CH}_4\)**: The most abundant hydrocarbon in natural gas, highly efficient for energy production.
• **Ethane \(\text{C}_2\text{H}_6\)**: Second most common, mainly used to produce ethylene which is a precursor to many plastics.
• **Propane \(\text{C}_3\text{H}_8\)**: Heavily used as a fuel, particularly in rural areas lacking natural gas pipelines.
• **Butane \(\text{C}_4\text{H}_{10}\)**: Known for its application in cigarette lighters and portable stoves due to its ability to be easily liquefied.
• **Isobutane \(\text{C}_4\text{H}_{10}\)**: Isomer of butane, commonly used as a refrigerant and in the production of gasoline.

Each of these hydrocarbons has unique properties and uses, underlining the importance of natural gas in various domains. These compounds help cover energy needs and serve essential roles in manufacturing and chemical production.
We also see why understanding their presence in natural gas is crucial for applications in both energy and industrial contexts. The problem mentioned highlights these common hydrocarbons, differentiating them from other compounds such as 2-methylbutane or cyclopropane, which are not typical components of natural gas.