AQA GCSE FOUNDATION Chemistry: Exothermic Reactions

AQA GCSE Foundation Chemistry: Exothermic Reactions

What are Exothermic Reactions?

Exothermic reactions are chemical reactions that release energy into the surroundings. This energy is usually released as heat, making the surroundings warmer. Think of it like burning a log in a fireplace - the burning log releases heat, making the room warmer.

Characteristics of Exothermic Reactions:

• Release of heat: The most obvious characteristic of an exothermic reaction is the release of heat, causing the surroundings to become warmer.
• Temperature increase: The temperature of the reaction mixture will increase as heat is released.
• Negative enthalpy change: In chemistry, we use a term called "enthalpy change" to describe the energy change in a reaction. For exothermic reactions, the enthalpy change is negative, indicating energy is released.

Examples of Exothermic Reactions in Daily Life:

Exothermic reactions are all around us! Here are some common examples:

• Burning fuels: When you burn wood, gas, or oil, these fuels react with oxygen, releasing heat and light. This is why we use fuels to heat our homes and power our cars.
• Explosions: Explosions are extremely rapid exothermic reactions that release a large amount of energy in a short time, creating a sudden expansion of volume.
• Hand warmers: Hand warmers contain chemicals that react exothermically, releasing heat and keeping your hands warm.
• Neutralization reactions: When an acid reacts with a base, heat is released, and the reaction mixture warms up.
• Respiration: Our bodies use exothermic reactions to break down food and release energy for our cells.

Identifying Exothermic Reactions:

You can identify an exothermic reaction by looking for these signs:

• Feeling of warmth: If you touch the reaction container, it will feel warm.
• Production of light: Some exothermic reactions produce light, like burning a candle.
• Release of bubbles: Some exothermic reactions produce gas bubbles.

Understanding Exothermic Reactions:

Exothermic reactions are an important part of our world, from providing us with energy to powering our bodies. Understanding how they work can help us appreciate the chemistry that surrounds us.