An endothermic reaction absorbs thermal energy from its surroundings. This causes the surroundings to feel cooler, just like when you feel a chill after a cold shower! ❄️
Think of an endothermic reaction as a scoop of ice cream melting in your hand. The ice cream takes heat from your hand (the surroundings) to melt, so your hand feels colder. The reaction’s enthalpy change is \$ΔH > 0\$.
An exothermic reaction is like a campfire: it releases heat into the surroundings, making the air feel warm. The reaction’s enthalpy change is \$ΔH < 0\$. 🔥
| Feature | Exothermic | Endothermic |
|---|---|---|
| Heat Flow | Out of the reaction | Into the reaction |
| ΔH | \$ΔH < 0\$ | \$ΔH > 0\$ |
| Surroundings Temperature | Increases | Decreases |
| Common Example | Combustion of wood | Melting of ice |
When you see a reaction that absorbs heat (e.g., dissolving ammonium nitrate in water), remember: \$ΔH > 0\$ and the surroundings feel cooler. Use the word “endothermic” to label it in your answer. 📘