Question

Spontaneous combustion is a special case of combustion where a material burns without heat being supplied from an external source. For example, a piece of phosphorus suddenly starts burning when kept in a dish on a table.


What could be the LIKELY reason for spontaneous combustion to happen?


1 Non-metals absorb heat from the atmosphere more quickly than metals and are likely to combust spontaneously because of this.

2 Materials that combust spontaneously have a special property- they need not reach the ignition temperature to combust.

3 Spontaneous combustion is a process that requires only the presence of the combustible substance; heat and oxygen are not required.

4 In the case of substances that combust spontaneously, a chemical reaction takes place which generates the heat required for combustion.

Answer 1

Explanation:

Introduction

People generally use wood, cowdung cakes, crop residues, kerosene oil, coke or LPG gas to cook food. For ruining vehicles, we use petrol or diesel oil. In factories, we use coal or fuel oil or natural gas.

The materials, such as wood, coke, LPG (liquid petroleum gas), petrol, diesel, natural gas have one property [n common, i.e., they produce heat on burning which is then put into different uses. Furthermore, some materials on burning produce flame and some do not. For example, a candle or coal gas on burning produces a flame, but not the coal or charcoal. So, let us study the chemical process of burning and the types of flame produced during this process.

Combustion

Some substances, like magnesium catches fire and burns with a dazzling white flame when heated in air. Similarly, when a piece of per is brought near a candle flame, it burns, producing heat and light. The charcoal and coal bums in air producing carbon dioxide, heat and light.

Air or oxygen which helps in burning is called supporter of combustion and the chemical reaction which takes place with the release of heat and light energy is called combustion.

A chemical process in which a substance reacts with oxygen to give off heat is called combustion.