What is the difference between intensive and extensive properties? For a substance, what is the difference between mass and molar mass? How are these two related?
The correct answer and explanation is :
Difference Between Intensive and Extensive Properties:
Intensive properties are those that do not depend on the amount or size of the substance. These properties remain constant regardless of the sample’s quantity. Examples include temperature, pressure, density, boiling point, and color. Intensive properties are useful in identifying substances since they are inherent to the material itself.
On the other hand, extensive properties are those that depend on the quantity or size of the substance. These properties change with the amount of material. Examples include mass, volume, energy, and enthalpy. Extensive properties are additive, meaning they increase with the amount of substance present.
Mass vs. Molar Mass:
- Mass refers to the quantity of matter in a substance. It is an extensive property, meaning it depends on the amount of substance. It is measured in kilograms (kg), grams (g), or other units of mass.
- Molar Mass is the mass of one mole of a substance. It is an intensive property because it remains constant regardless of the amount of substance. Molar mass is typically measured in grams per mole (g/mol). It tells you how much one mole of a given substance weighs and is calculated by summing the atomic masses of all elements in a molecule.
Relation Between Mass and Molar Mass:
The relationship between mass and molar mass is straightforward. If you know the mass of a substance and its molar mass, you can calculate the number of moles of that substance. The formula is:
[
\text{Number of moles} = \frac{\text{Mass of substance}}{\text{Molar Mass}}
]
For example, if the molar mass of water (H₂O) is approximately 18 g/mol and you have 36 grams of water, you would have:
[
\text{Number of moles} = \frac{36 \, \text{g}}{18 \, \text{g/mol}} = 2 \, \text{moles of water}
]
The mass tells you the total amount of material, while the molar mass allows you to relate it to the number of moles, which is useful in chemical reactions.
Here is a diagram that illustrates the differences between intensive and extensive properties, along with the relationship between mass and molar mass. The diagram highlights key examples and shows how these concepts are related, providing a clear visual representation.