Question

When hydrogen burns in oxygen, water is formed. When water is electrolysed, then hydrogen and oxygen are produced. What type of chemical reactions has occurred in both cases?

Answer 1

Step 1: Combination reaction:

When two or more compounds combine to form a single compound is called a combination reaction.

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Step 2: Decomposition reaction:

When a reactant dissociates to give two or more products, this type of reaction is called a decomposition reaction.

$2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

Step 3: Types of reaction

• Hydrogen burns in oxygen is a combination reaction.
• When water is electrolyzed, it produces hydrogen and oxygen, is a type of decomposition reaction.