Exothermic Combination Reaction

Combination reactions are those in which two or more substances combine to form a single product. When a combination reaction releases heat, it is called an exothermic combination reaction. One example of such a reaction is:

2H2 (g) + O2 (g) → 2H2O (l) + energy

This is the reaction of hydrogen gas and oxygen gas to form water. This reaction is highly exothermic, meaning that it releases a lot of energy in the form of heat. The energy released is due to the formation of new chemical bonds between the hydrogen and oxygen atoms to form water molecules.

Explanation of the Reaction

The balanced chemical equation for this reaction shows that two molecules of hydrogen gas (H2) react with one molecule of oxygen gas (O2) to form two molecules of water (H2O). The reaction releases energy in the form of heat, which is represented by the energy term on the right-hand side of the equation.

In this reaction, the hydrogen and oxygen atoms combine to form new chemical bonds between the H and O atoms in water molecules. The formation of these new bonds releases energy, which makes the reaction exothermic.

Conclusion

In conclusion, the combination reaction of hydrogen gas and oxygen gas to form water is an example of an exothermic reaction. This reaction releases a lot of energy in the form of heat due to the formation of new chemical bonds between the hydrogen and oxygen atoms to form water molecules. The balanced chemical equation for this reaction shows that two molecules of hydrogen gas react with one molecule of oxygen gas to form two molecules of water, along with energy as a product.

When quicklime or calcium oxide (CaO) reacts with water, slaked lime [Ca(OH)2​] is formed. During this reaction, a large amount of heat is released. So, this reaction is an exothermic Reaction.
calciciumoxide(quicklime)CaO(s)​+waterH2​O(l)​→calciumhydroxide(slakedlime)Ca(OH)2​(aq)+heat​