Superheating happens when a liquid is heated above its normal boiling point but does not immediately boil or form vapor bubbles. This can occur under very smooth conditions or in a clean container where there are no impurities or surfaces to trigger bubble formation.
Why superheating happens:
- Boiling requires the formation of vapor bubbles within the liquid.
- Without nucleation sites (like scratches or particles), bubbles can’t easily form.
- As a result, the liquid’s temperature rises above its boiling point without vaporization.
Risks and examples:
- Superheated water in a microwave can suddenly and violently boil when disturbed, posing a burn hazard.
- This phenomenon is important in industrial processes and lab settings where controlled boiling is necessary.
Superheating illustrates that boiling is not just about reaching a temperature, but also about the conditions that allow phase change to start.