Examples of Exothermic Reactions:

Combustion of Methane:
- CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + energy
- In this reaction, methane (CH4) reacts with oxygen (O2) to produce carbon dioxide (CO2), water (H2O), and energy. This reaction releases heat energy, making it an exothermic reaction.
- The energy released during the combustion of methane is in the form of heat, making it useful for heating applications such as cooking and heating homes.

Neutralization of Hydrochloric Acid and Sodium Hydroxide:
- HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) + energy
- When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it forms sodium chloride (NaCl), water (H2O), and releases energy. This reaction is exothermic as it releases heat.
- The heat released during this neutralization reaction can be felt, making it useful in hand warmers and other heat-generating applications.

Decomposition of Hydrogen Peroxide:
- 2H2O2(aq) → 2H2O(l) + O2(g) + energy
- Hydrogen peroxide (H2O2) decomposes into water (H2O), oxygen gas (O2), and releases energy in the form of heat. This reaction is exothermic.
- The heat released during the decomposition of hydrogen peroxide can be used in chemical warmers and other heat-generating devices.
In an exothermic reaction, the products have lower energy than the reactants, resulting in the release of heat energy. These reactions are important in various industrial processes, energy production, and everyday applications where heat is needed.