Question

Under similar conditions of temperature and pressure, the ratio of the rate of diffusion of methane and Sulphur dioxide is 2:1

• A. True
• B. False

Answer 1

The correct option is B False

• Diffusion is the passive movement of a substance from an area of higher concentration to a lower concentration till a dynamic equlibrium is achieved.
• According to Graham's law of diffusion, the rate of diffusion of a gas is inversely proportional to the square root of the mass of the particles.

$\frac{{\mathrm{r}}_1}{{\mathrm{r}}_2}$ ∝ $\sqrt{\frac{{\mathrm{M}}_2}{{\mathrm{M}}_1}}$

Where r₁, r₂ are rates of diffusion of gases 1 and 2 respectively. M₁ and M₂are the molar masses of the two gases.

• Molecular mass of Methane CH₄ = 12+ (1×4) =16 g
• Molecular mass of Sulphur dioxide (SO₂) =32+ (16×2)=32+32=64g

Since $\frac{{\mathrm{r}}_1}{{\mathrm{r}}_2}$ = $\sqrt{\frac{{\mathrm{M}}_2}{{\mathrm{M}}_1}}$ =$\frac{{\mathrm{r}}_{{\mathrm{SO}}_2}}{{\mathrm{r}}_{{\mathrm{CH}}_4}}$ =$\sqrt{\frac{{\mathrm{M}}_{{\mathrm{CH}}_4}}{{\mathrm{M}}_{{\mathrm{SO}}_2}}}$ = $\sqrt{\frac{16}{64}}$=$\sqrt{\frac{1}{4}}$= $\frac{1}{2}$= 1:2

• Hence under similar conditions of temperature and pressure, the ratio of the rate of diffusion of Methane and Sulphur dioxide is 1:2.

So, under similar conditions of temperature and pressure, the ratio of the rate of diffusion of methane and Sulphur dioxide is 2:1, this is a false statement.