Question

What is the reaction between hydrogen and oxygen?

Answer 1

Hint: Hydrogen is a highly reactive fuel. Hydrogen molecules violently react with oxygen when the existing molecular bonds break and new bonds are formed between oxygen and hydrogen atoms. As the products of the reactions are at lower energy levels than the reactants.

Complete answer:
When molecular hydrogen $$(H_2)$$ and oxygen $$(O_2)$$ are combined and allowed to react together, energy is released and the molecules of hydrogen and oxygen can combine to form either water or hydrogen peroxide. In the reaction, the hydrogen molecules are oxidized and the oxygen atoms are reduced.
Hydrogen and oxygen are at a higher energy level than the products of the reaction. This results in the net release of energy from the reaction, and this is known as an exothermic reaction. After one set of hydrogen and oxygen molecules have reacted, the energy released triggers molecules in the surrounding mixture to react, releasing more energy. The result is an explosive, rapid reaction that releases energy quickly in the form of heat, light and sound.
$$2H_2+O_2\to 2H_{2}O+Heat$$
The reason for the difference in energy level between the reactants and products lies with electronic configuration. Hydrogen atoms have one electron each. They combine into molecules of two so that they can share two electrons. This is because the innermost electron shell is at a lower energy state when occupied by two electrons. Oxygen atoms have eight electrons each. They combine together in molecules of two by sharing four electrons so that their outermost electron shells are fully occupied by eight electrons each.

Note:
Hydrogen and oxygen creates a new molecule, the product of the reaction in water and heat. The heat can be harnessed to do work, such as driving turbines by heating water. The products are produced quickly due to exothermic conditions. For molecules to exchange electrons tied to a molecule have to be broken, the energy required to break the bond is known as activation energy.