Evaporation vs. Boiling: What's the Difference?

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Read the comparison below, or explore it visually. Create a visual lesson comparing evaporation and boiling using available credits or plan allowance.

Evaporation is the slow escape of molecules from a liquid's surface at any temperature, while boiling is rapid vaporisation throughout the liquid that happens only at its boiling point. In boiling, bubbles of vapour form inside the liquid because its vapour pressure has risen to equal the pressure of the air above it; in evaporation, only the fastest molecules at the surface break free.

At a glance

	Evaporation	Boiling
Temperature	Any temperature below the boiling point	Only at the boiling point
Where it occurs	Only at the liquid's surface	Throughout the liquid, forming bubbles
Speed	Slow and quiet	Fast and vigorous
Effect on temperature	Cools the remaining liquid	Temperature stays constant while it boils
Energy source	Surroundings and the liquid itself	A continuous external heat supply

Which should you use?

Evaporation

Evaporation explains everyday drying and cooling, such as wet clothes drying on a line or water in an earthen pot (matka) staying cool as it seeps out and evaporates.

Boiling

Boiling applies when a liquid is heated until bubbles form throughout it, such as water on a stove reaching about 100 °C at sea level to cook rice or sterilise milk bottles.

Frequently asked questions

Why does evaporation cause cooling?

Evaporation removes the fastest-moving molecules from the surface. The molecules left behind have a lower average kinetic energy, so the liquid's temperature falls. The same effect cools your skin as sweat evaporates and keeps water cool in an earthen pot.

Why does water boil at a lower temperature in the mountains?

Air pressure is lower at high altitude, so water's vapour pressure reaches it at a lower temperature. Water therefore boils below 100 °C, and food cooks more slowly. A pressure cooker works the other way, raising the pressure so water boils above 100 °C.

What factors increase the rate of evaporation?

Four main factors: a larger surface area, a higher temperature, lower humidity and more wind. Spreading wet clothes out on a hot, dry, breezy day dries them fastest, because more molecules escape and the moist air near the cloth is carried away.