Boiling Point

The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the external pressure surrounding the liquid, and the liquid changes into a gas. It is a characteristic physical property of a substance and can be used to identify and differentiate between different substances.

Factors Affecting Boiling Point

The boiling point of a substance is influenced by several factors, including:

1. Intermolecular Forces: Substances with stronger intermolecular forces generally have higher boiling points because more energy is required to overcome these forces and convert the substance into a gas.
2. Molecular Weight: Heavier molecules generally have higher boiling points compared to lighter molecules due to increased intermolecular forces.
3. External Pressure: The boiling point of a substance varies with changes in external pressure. At higher altitudes, where the atmospheric pressure is lower, the boiling point of a substance will be lower.
4. Purity: Impurities in a substance can lower its boiling point, as the presence of impurities disrupts the regular crystal lattice or intermolecular forces.

Boiling Point Study Guide

When studying the boiling point, it is important to consider the following key points:

1. Understand the concept of vapor pressure and its relationship to boiling point.
2. Learn how intermolecular forces affect boiling points and how to compare the boiling points of different substances based on their intermolecular forces.
3. Be familiar with the factors that can influence the boiling point of a substance, such as molecular weight, purity, and external pressure.
4. Practice identifying substances based on their boiling points and predicting the boiling points of different substances based on their molecular characteristics.

By mastering the concept of boiling point and its influencing factors, you can gain a deeper understanding of the physical properties of substances and their behavior under different conditions.