Which of the following is an example of an exothermic reaction?
A.
Melting ice
B.
Burning wood
C.
Cooking an egg
D.
Dissolving sugar in water
The correct answer and Explanation is :
The correct answer is B. Burning wood.
Explanation
An exothermic reaction is a chemical reaction that releases energy in the form of heat or light to its surroundings. This release of energy typically causes the temperature of the surrounding environment to increase. In contrast, endothermic reactions absorb energy from the surroundings, leading to a decrease in temperature.
Burning wood exemplifies an exothermic reaction. During combustion, wood reacts with oxygen in the air, producing carbon dioxide, water, and heat. This process involves breaking down the complex organic compounds found in wood (like cellulose and lignin) and rearranging them into simpler products, releasing energy in the form of heat. The heat released can ignite surrounding materials, making combustion a powerful example of an exothermic reaction.
In contrast, the other options listed represent endothermic or non-exothermic processes:
- A. Melting ice: This is an endothermic process, as it requires heat to break the hydrogen bonds between water molecules, allowing the solid ice to transform into liquid water.
- C. Cooking an egg: While cooking does involve a heat source, the process is primarily about denaturing proteins and can be considered neither distinctly exothermic nor endothermic since it doesn’t release energy to the environment but instead requires heat input.
- D. Dissolving sugar in water: This is also an endothermic process, where energy is absorbed from the surroundings to break the intermolecular forces in sugar, leading to a temperature drop in the solution.
In summary, burning wood is a clear example of an exothermic reaction due to the heat released during combustion, distinguishing it from the other processes listed.