how Avogadros hypothesis applied to show molecular mass of volatile substances is twice of Vapour density?
To understand how Avogadro's hypothesis applies to show that the molecular mass of volatile substances is twice their vapor density, we need to break down the concepts involved.
1. Avogadro's Hypothesis:
Avogadro's hypothesis states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules. In simpler terms, it suggests that the relative number of molecules in a gas is directly related to the volume it occupies.
2. Molecular Mass:
The molecular mass of a substance is the mass of one molecule of that substance, expressed in atomic mass units (amu). It gives you the total mass of all the atoms in a molecule.
3. Vapor Density:
Vapor density is the ratio of the mass of a given volume of a gas compared to the mass of an equal volume of a reference gas, usually hydrogen (H₂). It helps determine the relative molecular mass of the substance compared to the reference gas.
Now, let's see how these concepts relate to each other:
- According to Avogadro's hypothesis, equal volumes of gases contain an equal number of molecules.
- The molecular mass of a substance is the combined atomic mass of the atoms in its molecule.
- The vapor density compares the mass of a gas to an equal volume of hydrogen gas.
Considering these points, here's how we can show that the molecular mass of volatile substances is twice their vapor density:
1. Take a volatile substance and measure its vapor density.
2. As per Avogadro's hypothesis, the same volume of the volatile substance and hydrogen gas contains an equal number of molecules.
3. Since the two gases occupy the same volume, their masses will be directly proportional to the molecular masses.
4. The vapor density of the volatile substance is then reflected in terms of the relative mass compared to hydrogen.
5. The molecular mass of the volatile substance is twice its vapor density, as the volatile substance and hydrogen molecules are equal in number and occupy the same volume.
Therefore, the molecular mass of a volatile substance is twice its vapor density, as per Avogadro's hypothesis.