NCERT Solutions for Class 8 Science Chapter 4 Combustion and Flame
Page No. 51 Exercise Question 4.
8th Science Chapter 4 Combustion and Flame
NCERT Academic Session 2023-2024
CBSE Board and Others state Board
Description:
Fuels are substances providing energy through combustion. They include fossil fuels (coal, oil, gas) and renewable sources (biomass, solar, wind). Used for transportation, electricity, heating, and industry, fuels vary in energy content, combustibility, and environmental impact, prompting a shift towards cleaner, renewable alternatives for sustainability.
LPG (Liquefied Petroleum Gas) and wood are two commonly used fuels, each with distinct characteristics that make them suitable for various applications.
Calorific Value:
LPG boasts a higher calorific value, typically ranging from 46,000 kJ/kg to 50,000 kJ/kg. In contrast, wood’s calorific value varies more widely, falling within the range of 15,000 kJ/kg to 22,000 kJ/kg.
Efficiency:
When it comes to efficiency, LPG shines. It burns more cleanly and consistently, offering a more efficient energy output. Wood, on the other hand, may exhibit less consistent combustion due to variable moisture content and combustion conditions.
Convenience:
The convenience factor favors LPG. Packaged in tanks or cylinders, it offers ease of use, instant ignition, and the ability to regulate heat with precision. Wood, while readily available, requires more preparation time for chopping, seasoning, and igniting fires.
Cost and Availability:
LPG tends to be pricier but offers consistent availability. Wood, depending on sourcing and seasonality, can be more cost-effective but might suffer from availability fluctuations.
Environmental Impact:
LPG is considered a cleaner-burning fuel, emitting fewer pollutants compared to wood, which can produce smoke, particulates, and carbon dioxide when burned.
Application:
LPG finds widespread use in heating, cooking, and industrial processes due to its high energy content and convenience. Wood is primarily utilized for residential heating in fireplaces and wood stoves, as well as some cooking applications.
In summary, LPG presents itself as a more efficient, cleaner, and convenient option, albeit at a higher cost. Wood, although potentially cheaper, demands more effort, may have environmental implications, and possesses a lower energy content. Deciding between the two often hinges on factors such as availability, cost, convenience, and environmental concerns.