Question

Extensive properties depend on the quantity of matter but intensive properties do not.

Explain whether the following properties are extensive or intensive. Mass, internal energy, pressure, heat capacity, molar heat capacity, density, mole fraction, specific heat, temperature and morality.

Answer 1

If the value of any property is changed by changing the amount of substance, it is an extensive property but if it is unchanged by changing amount, it is an intensive property. The ratio of two extensive property is intensive i.e., Extensive / Extensive = Intensive.

1) Mass:- It depends on the amount of substance present in system.

$\therefore$ It is an extensive property.

2) Internal energy:- The magnitude of internal energy depends on the amount of substances.

$\therefore$ It is an extensive property.

3) Pressure:- It is the ratio of force by area. $ForceF=mass\times acceleration$

Product of an extensive and intensive property is an extensive property. Hence force is an extensive property and area is also an extensive property.

We know that the ratio of two extensive properties is intensive.

$\therefore$ Pressure is an intensive property.

4) Heat Capacity (C):- It depends upon the size and quantity of the sample

$\therefore$ It is an extensive property

5) Molar heat capacity:- It does not depend upon size and mass sample. It is the ratio of extensive properties- heat capacity $\left(C\right)$ and number of mole$\left(n\right)$:

$C_m\left(molarheatcapacity\right)=\frac{C}{n}$

$\therefore$ It is an intensive property.

6) Density:- It is ratio of two extensive properties i.e., mass/volume.

$\therefore$ It is an intensive property.

7) Mole fraction:- It is an intensive property as it is also ratio of number of moles of one substance upon the total number of moles.

$\therefore$ It is an intensive property.

8) Specific heat capacity (c):- It is the quantity of heat required to raise the temperature of one unit mass of a substance by $1^{\circ }C/1K$.

Since it is defined per mole, it is an intensive property.

9) Temperature:- It does not depend upon size and mass of sample

$\therefore$ It is an intensive property.

10) Molarity (M):- It is the ratio of two extensive properties i.e.,

$\text{Molarity}=noofmoles/VolumesinL$

$\therefore$ It is an intensive property.