🥶Endothermic vs Exothermic🔥
Reactions either take in or give out energy. The sign of the enthalpy change tells you which, and energy diagrams make it visual.
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🥶Endothermic
- ✓Absorbs heat from the surroundings
- ✓Enthalpy change is positive
- ✓Products have more energy than reactants
- ✓Surroundings get colder
- ✓Examples: photosynthesis, ice melting
🔥Exothermic
- ✓Releases heat to the surroundings
- ✓Enthalpy change is negative
- ✓Products have less energy than reactants
- ✓Surroundings get warmer
- ✓Examples: combustion, neutralization
Verdict
Endothermic reactions absorb energy and feel cold; exothermic reactions release energy and feel hot. The sign of ΔH tells you instantly which category applies.
Frequently asked
How does the sign of ΔH help?+
A positive ΔH means endothermic (heat absorbed); a negative ΔH means exothermic (heat released).
Why does an instant cold pack feel cold?+
It uses an endothermic dissolving process that absorbs heat from your skin.
Is combustion endo or exothermic?+
Combustion is strongly exothermic, releasing large amounts of heat and light.
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