Boiling point

Definition

The boiling point is the temperature at which a liquid's vapor pressure equals the external pressure surrounding the liquid. At this temperature, the liquid transitions to a gas phase.

5 Must Know Facts For Your Next Test

1. Boiling point varies with atmospheric pressure; it is lower at higher altitudes.
2. Impurities in a liquid can raise or lower its boiling point due to changes in vapor pressure.
3. The normal boiling point of a substance is measured at 1 atmosphere (atm) of pressure.
4. Boiling is an endothermic process, requiring energy input to break intermolecular forces.
5. Different substances have different boiling points based on their molecular structure and intermolecular forces.

Review Questions

• How does atmospheric pressure affect the boiling point of a liquid?
• What happens to the molecules of a liquid when it reaches its boiling point?
• Why do substances with stronger intermolecular forces have higher boiling points?

Related terms

Vapor Pressure: The pressure exerted by a vapor in equilibrium with its liquid or solid phase.

Phase Transition:

A change from one state of matter (solid, liquid, gas) to another.

Normal Boiling Point: The temperature at which a liquid boils under standard atmospheric pressure (1 atm).