Avogadro's Law: Equal Volumes, Equal Molecules
Definition
Avogadro's law
Avogadro's law states that equal volumes of all gases, measured under the same conditions of temperature and pressure, contain equal numbers of molecules.
- This principle is grounded in the idea that the volume of a gas depends on the number of particles it contains, regardless of their type or size.
- Whether the gas consists of single atoms (e.g., helium, He), diatomic molecules (e.g., oxygen, $O_2$, or larger molecules (e.g., carbon dioxide, $CO_2$, Avogadro's Law holds true.
Mathematical Expression of Avogadro's Law
- The relationship described by Avogadro's Law can be expressed mathematically as: $$\frac{V_1}{n_1} = \frac{V_2}{n_2}$$ where:
- $V_1$ and $V_2$ are the volumes of two gas samples.
- $n_1$ and $n_2$ are the amounts of gas (in moles) in the respective samples.
- This equation shows that the volume of a gas is directly proportional to the number of moles, provided the temperature and pressure remain constant.
When solving gas stoichiometry problems, you can use Avogadro's Law to relate volumes directly, without needing to calculate the number of moles.
