Boiling Point
The boiling point of an element or a substance can be defined as the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. Boiling point is the temperature at which a liquid changes to a gas (vapor) at normal atmospheric pressure.
This is the temperature at which a substance goes from the liquid state to the gaseous state at normal atmospheric pressure (760 mm Hg (101.32 kPa)).
The boiling point of water is at 212° F or 100°C.
There is a direct relationship between boiling point and atmospheric pressure. The lower the atmospheric pressure, the lower the boiling point. The higher the atmospheric pressure, the higher the boiling point.
The intermolecular forces that exist between molecules affect its boiling point.
If the intermolecular forces are relatively strong, the boiling point will be relatively high.
If the intermolecular forces are relatively weak, the boiling point will be relatively low.
When the external pressure is equal to one atmosphere (760 torr), the boiling point of a liquid is called the normal boiling point.
The normal boiling point is also called the atmospheric boiling point or the atmospheric pressure boiling point.