Steam can burn far worse than boiling water because it carries extra hidden heat.

The longer version

Turning liquid water into vapour takes a large amount of energy that is stored invisibly in the gas. When that vapour touches cooler skin it condenses back into liquid and hands the stored energy over in an instant. The burn therefore combines the heat of very hot water with the extra energy released on contact.

Boiling water alone only carries the heat it took to reach its temperature. The vapour carries that plus the hidden cost of the change of state, which is considerable. Because the gas also spreads widely and clings to surfaces, the affected area tends to be larger than a simple splash would produce.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.

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More From Science and Physics

Eight more entries

Metal feels colder than wood at the same temperature since it draws heat away faster.

Dark clothing absorbs more sunlight than pale clothing, which is why summer shirts feel hotter.

A microwave heats food by making water molecules inside it vibrate and warm their surroundings.

Refrigerators cool food by moving heat outward rather than by creating coldness from nothing.

Pressure cookers raise the boiling point of water so food cooks faster than usual.

Sound travels roughly four times faster through water than it does through ordinary air.

Sound cannot travel through a vacuum because there are no particles to carry the vibration.

Bats navigate dark caves by listening to echoes of their own high-pitched calls.

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