In chemical reactions, exothermic reactions release heat energy to the surroundings, while endothermic reactions absorb heat energy from the surroundings. Think of it this way: if a reaction feels warm or the temperature rises, it’s likely exothermic; if it feels cold or the temperature drops, it’s endothermic.
Exothermic Reactions:
Definition: Reactions that release heat energy to the surroundings.
Examples:
Burning fuel: Combustion reactions, like burning wood or coal, release a significant amount of heat and light.
Neutralization reactions: When an acid and a base react, they produce heat.
Reactions between strong acids and water: For example, the reaction of sulfuric acid with water is exothermic.
Endothermic Reactions:
Definition: Reactions that absorb heat energy from the surroundings.
Examples:
Melting ice: Melting ice cubes absorbs heat from the surrounding environment, causing the ice to melt and the surrounding air to feel cooler.
Photosynthesis: Plants use light energy from the sun to convert carbon dioxide and water into sugar and oxygen, a process that absorbs heat.
Decomposition of calcium carbonate: When heated, calcium carbonate breaks down into calcium oxide and carbon dioxide, requiring energy input in the form of heat.