What is an exothermic reaction? Combustion of fuel is an exothermic process. Explain why by providing an example of a fuel. Give 3 examples of readily observable reactions that are considered exothermic. In each example, describe the reactants and the products.

An exothermic reaction is a chemical reaction in which energy is given out to the surroundings in the form of heat or light or even sound.

Other explanations are given below.

Explanation:

An exothermic reaction is a chemical reaction in which energy is given out to the surroundings in the form of heat or light or even sound. In exothermic reactions, the energy content of the products are lower than that of the reactants and this excess energy is therefore released as the reaction proceeds towards formation of products.

Combustion of fuel is an exothermic reaction because the process involves the  release of energy in the form of heat and light to the surroundings as the reactants (usually a fuel and oxygen) which are at a higher energy state combine to give the products which are at a lower energy state (usually CO₂ and water).

An example of a fuel is the gas propane found in cooking gas. It combines with oxygen found in air to produce the heat that is used to cook our foods.

Other examples of exothermic reactions include

1.Lighting firewood: In this process, wood which is a mixture of gaseous fuels like methane and solid fuel like charcoal combine with oxygen found in air to produce carbon (iv) oxide and water vapor while releasing heating the process.

2. Lighting a match: The head of safety matches are made of potassium chlorate, mixed with sulfur, fillers and glass powder.  The side of the box contains red phosphorus, binder and powdered glass. When the match is struck, the friction generates heat which causes a small amount of red phosphorus to be converted to white phosphorus, which then ignites spontaneously in air.  The heat produced initiates the decomposition of potassium chlorate to give oxygen and potassium chloride.  The sulfur catches fire and ignites the wood which also burns in the air to release carbon (iv) oxide an water.

3. Burning of coal: Coal is solid carbon which combines with oxygen in air when ignited to produce carbon (iv) oxide and water vapor while also releasing heat and light energy.

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