Chemistry is the science of change. At the heart of these changes lie chemical reactions, where substances transform into new substances. Two fundamental types of chemical reactions are exothermic and endothermic reactions.
Exothermic reactions release energy, usually in the form of heat. This energy is what warms your hands when you activate a hand warmer or what ignites fireworks in the sky. On the other hand, endothermic reactions absorb energy from their surroundings. This process is why you feel instantly cool when you put rubbing alcohol on your skin; it's absorbing the heat from your body!
These reactions are crucial in our world. For instance, photosynthesis, the process that feeds nearly all life on earth, is an endothermic reaction where plants absorb energy from sunlight to convert carbon dioxide and water into glucose and oxygen. Meanwhile, the combustion of fossil fuels, which powers our cars and homes, is an exothermic reaction.
You can even observe these reactions at home. Try dissolving citric acid (found in citrus fruits) and baking soda in water. You'll feel the solution getting cooler, indicating an endothermic reaction.
Understanding these reactions is essential for scientists to create new materials, develop clean energy sources, and even cook your favorite dishes. So, the next time you feel warmth from a campfire or chill from a cold pack, remember - it's all chemistry at work!