Problem 9 - A Complete Resource Book in Chemistry for JEE Main

Question

Household fuel (LPG) mainly contains (a) \(\mathrm{CH}_{4}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{2}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{4}^{4}\) (d) \(\mathrm{C}_{4}{\underline{\phantom{xx}}}^{2} \mathrm{H}_{10}\)

Step-by-Step Solution

Answer

Household fuel (LPG) mainly contains (d) \\(\mathrm{C}_{4}\mathrm{H}_{10}\\).

Step 1: Identify Primary Components of LPG

LPG, or liquefied petroleum gas, is primarily composed of hydrocarbon gases. The main components of LPG are propane and butane.

Step 2: Match Chemical Formulas

Compare the options provided with the chemical formulas of propane and butane. Propane is \( ext{C}_3 ext{H}_8\) and butane is \( ext{C}_4 ext{H}_{10}\).

Step 3: Select the Correct Option

After matching the formulas, option (d) \( ext{C}_4 ext{H}_{10}\), which represents butane, matches one of the main components of LPG.

Key Concepts

Hydrocarbons

Hydrocarbons are organic compounds consisting entirely of hydrogen and carbon. They are a significant category in chemistry due to their role as the primary constituents of fossil fuels like natural gas, petroleum, and coal. In terms of LPG, hydrocarbons are crucial because LPG mostly comprises two specific hydrocarbon gases: propane and butane.

Hydrocarbons are divided into different classes based on the type of bonding between the carbon atoms:

• Alkanes: These have single bonds between carbon atoms, like in propane and butane.
• Alkenes: These contain at least one double bond.
• Alkynes: These feature triple bonds.
• Aromatics: Known for their distinct ring structures.

Because alkanes like propane (C₃H₈) and butane (C₄H₁₀) are saturated hydrocarbons, they are fully saturated with hydrogen atoms and have only single covalent bonds. This saturation makes them more stable and less reactive compared to unsaturated counterparts, making them ideal for fuel applications.

Propane

Propane is a three-carbon alkane with the chemical formula C₃H₈. It is a common component of liquefied petroleum gas (LPG).

Because propane is a hydrocarbon, it is considered a fossil fuel and is used widely due to its energy efficiency and cleaner burning properties compared to some other fossil fuels, such as coal.

Key uses for propane include:

• Heating: Used in home heating, hot water systems, and cooking.
• Fuel: Employed as engine fuel, particularly in internal combustion engines.
• Industrial Applications: Powers various manufacturing processes.

Propane is liquefied under moderate pressure, making it easy to transport and store in cylinders for residential or commercial use.

Butane

Butane is another important alkane, made up of four carbon atoms with the chemical formula C₄H₁₀. It serves as a primary component of LPG, similar to propane.

One significant characteristic of butane is that it can exist in two structural forms: n-butane and isobutane. These are known as isomers, which are compounds with the same chemical formula but different structural arrangements.

Applications of butane include:

• Fuel: Utilized in portable stoves, lighters, and heaters.
• Aerosol Propellant: Employed in sprays and foams due to its ability to evaporate quickly.
• Refrigerant: Used in refrigeration systems as an eco-friendly option.

When used in LPG, butane provides a high-energy density, making it and propane an efficient and versatile energy source for various uses.