Question

From a certain apparatus, the diffusion rate of hydrogen has an average value of 28.7 cm³ s⁻¹. The diffusion of another gas under the same conditions is measured to have an average rate of 7.2 cm³ s⁻¹. Identify the gas.

Answer 1

given,
diffusion rate of hydrogen gas = 28.7cm³/s
diffusion rate of unknown gas = 7.2 cm³/s

we know, from Graham's law of diffusion of gases.
rate of diffusion is inversely proportional to square root of their density or molecular mass.
e.g., $r\propto\frac{1}{\sqrt{M}}$

we can write it in $\frac{r_1}{r_2}=\sqrt{\frac{M_2}{M_1}}$

here, $r_1=28.7cm^3/s,r_2=7.2cm^3/s,M_1=2g/mole,M_2=?$

$\frac{28.7}{7.2}=\sqrt{\frac{M_2}{2}}$

$3.986\approx4=\sqrt{\frac{M_2}{2}}$

taking square both sides,

16 = $\frac{M_2}{2}$

$M_2=16\times2=32g/mole$

we know, molecular mass of oxygen is 32g/mole. so, unknown gas is oxygen.

Answer 2

Answer:

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