Question

Graham’s law refers to which of the following?
(A) Gaseous diffusion
(B) Boiling point of gases
(C) Gas compression problems
(D) Volume changes of gases when the temperature changes

Answer 1

Hint: Gaseous particles, which are in constant random motion. These particles are tending to undergo diffusion because they have kinetic energy. At high temperatures, diffusion is faster because the gas molecules have greater kinetic energy. The movement of gas particles through a small hole refers to effusion.

Complete answer:
Effusion:
This is a process in which air escapes or leaks through a hole whose diameter is less than the mean free path of molecules. This effusion is the escape of gaseous particles through a small hole like a small balloon, into an evacuated space.
Diffusion:
This is a phenomenon where there is a movement of one material moving from a high concentration area to a low concentration area and which means particles or molecules spread through the medium. The resulting diffusion in gases mixture forms uniform composition.
According to graham’s law, molecules or atoms with lower molecular mass will effuse faster than the higher molecular mass at constant pressure and temperature.
The law states that the rate of diffusion or effusion is inversely proportional to its molecular mass.
There is a formula proposed by Grahams which is generally used to compare the rates of two different gases at equal pressure and temperature.
\[\dfrac{{{r}_{1}}}{{{r}_{2}}}=\sqrt{\dfrac{{{M}_{1}}}{{{M}_{2}}}}\]
Where, ${{M}_{1}}\And {{M}_{2}}$ are the molar masses of gas 1 and gas 2
${{r}_{1}}\And {{r}_{2}}$ are the rate of diffusion or effusion of the first gas and second gas.
Hence, Graham’s law refers to gaseous diffusion.

The correct answer is option A.

Note:
Gaseous diffusion means the spontaneous mixing of gases against gravitational forces to form a homogenous mixture. The rate of diffusion is the distance traveled by gas molecules per unit of time. Gaseous molecules at higher speed do not diffuse rapidly.