10 Examples of Exothermic Reaction in Everyday Life

Among all the different chemical reactions present, exothermic ones always seem to be the most physically appealing ones. This is because they are mostly associated with significant changes in form, rapid and visually attractive reactions, etc. 

An exothermic reaction can be simply defined as any chemical reaction that involves releasing energy in the form of heat or thermal energy. 

Here are a few interesting Examples of Exothermic Reactions in Everyday Life that can make this important chapter more interesting.

Formation of ice

A common example of this process is when the water in an ice tray is put inside a freezer. What happens within the molecules of water is a clear and interesting example of an exothermic reaction.

Water is composed of a vast number of molecules that are ideally under constant motion, thereby producing small amounts of energy at a constant rate due to their continuous motion. This directly translates to heat energy. 

When placed in a freezing cold environment, this water with molecules in constant movement slowly undergoes compression, letting out the heat from the water slowly in small amounts over some time. At some point along the process, the entire amount of heat energy possessed by the water molecules is lost, allowing ice cubes to form.

Exothermic Reaction in Everyday Life


This is one of the processes where the expulsion of heat can be appreciated visibly because of its significant physical expression. According to its chemical composition, the variant of quicklime used regularly in everyday life is called hydrated lime or just lime.

This lime is derived from quicklime through an exothermic reaction involving the conversion of calcium oxide or quicklime undergoing hydration to produce calcium hydroxide or lime.

The amount of heat generated by the reaction can be altered. Upon mastering the correct ratio of calcium oxide water to be mixed in the reaction, it is possible to create reactions that burst in an explosion. It is unsafe and to be avoided.

This is one of the reactions where the heat and reaction can actually be felt as a physical sensation by touching the reacting test tube or container. According to the amount of quicklime involved, one may even notice it visually.

Cellular respiration

Most of the routine metabolic reactions that take place within the cells in all living organisms are exothermic in nature as they burn out quite an amount of energy along with the end products of the reaction. 

The metabolism of sugars, mostly the ones ingested orally as a diet, are the ones that contribute hugely to the metabolically produced heat energy. It is even noticed physically as a feeling of excess warmth following a heavy, starchy meal. 

The presence of noticeable signs directly reflects the large amount of heat energy generated by the breakdown reactions of dietary sugars.

Setting of cement

This reaction, though very commonly occurring, is often left unnoticed. The reaction that occurs while mixing cement with water is basically a hydrating process. Going into more detail, one must know the simple composition of cement, which is as follows.

  • Di-calcium silicate
  • Tricalcium silicate
  • Calcium Aluminate

When water is mixed with cement, it reacts with these minerals, more specifically hydrates them, thereby forming the respective hydrates of appropriate minerals, giving out energy along the way in the form of heat.

The process explained above is the root principle as to why heavily burdened structures hold stable even after severe exposure to cold and wet climates. 

The constant amount of heat energy sent out by the process of cement setting prevents the excess collection of heat within the structure, thereby adding to their stability as excess heating might lead to cracks and breakage.

Laundry detergents

The basis of energy release associated with laundry detergent is similar to cement, except it involves sodium components.

Hot and cold packs

This is a commonly seen reaction when using a hot gel pack for several conditions faced quite regularly like headaches, cramps and muscle distress, etc. These packs generally possess two separate bags placed within each other. 

The bag on the inside is usually filled with water. The outer one holds ionic salts like magnesium sulphate and calcium chloride, which act as stimulants for the exothermic reaction.

When these packs are pressed against the affected area to heal, the water diffuses from the inner bag. It reacts with the ions present within the bag to release heat energy, producing a therapeutic healing effect and temporarily relieving pain.

Formation of snow in clouds

It is common information that the formation of clouds is by condensation and that a number of clouds precipitate the water in them and promote their conversion to ice. The formation of ice from water ultimately requires water molecules to spend energy moving closer, thereby releasing heat energy.

Lighting a match stick

The basic composition of a matchstick includes phosphorus, sulphur and a few other chemicals, which on the ignition, tend to react with the air around itself, producing a significant flame along with heat and light energy.

This principle holds for all other forms of combustion as well.

Burning of candles

The paraffin wax, a major component of candles, is composed of hydrocarbons that break down upon contact with oxygen. This reaction releases heat and warmth along with the production of the candle flame.

Epoxy resins

This is noticed when two epoxy resins are mixed as they undergo polymerisation. The new bonds formed during polymerisation lead to heat energy production, making the reaction exothermic.


In conclusion, exothermic reactions can be fascinating as they are commonly seen along different processes and tasks involved in everyday life. 

Exploring these reactions can be a fascinating thing to do. There are all types of exothermic reactions that happen in everyday surroundings ranging from safe and soft visually pleasing reactions to dramatic explosions. 

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