Name: Graham's Diffusion Law
Uploaded: 2019-07-19
Duration: 9 min 43 s
Description: Gases diffuse at a different rate. Watch this video to understand Graham's diffusion law, which deals with the diffusion of gases. Have fun learning!

Question

State and explain Dalton&rsquo;s law of partial pressure. What are its applications ?

Accepted Answer

Dalton's law of partial pressure states that the total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases in the mixture. And mathematically, it can be expressed as follows;

$P_{Total} = p_{1} + p_{2} + p_{3} + \dots \dots \dots \dots \dots (i)$ (at constant $T$ and $V$ )

Where $P_{Total} =$ The total pressure exerted by the mixture of gases.

and $p_{1}, p_{2}, p_{3 \dots \dots \dots \dots}$ are the partial pressures of gases.

Partial pressure can also be expressed in terms of mole fraction,

$p_{i} = X_{i} \times P_{Total}$

Where, $i = 1, 2, 3 \dots \dots \dots$

If the number of moles of first gas is $n_{1}$ and total number of moles of in gaseous mixture is $n_{Total}$ then mole fraction of $i^{th}$ gas

$X_{i} = \frac{n_{i}}{n_{1} + n_{2} + \dots \dots \dots \dots \dots \dots + n_{i}}$

There are following applications of Dalton's law of partial pressure,

$1 .$ Determination of pressure of dry gas-

Gases are generally collected over water and therefore are moist. And the Pressure of dry gas can be calculated by subtracting vapour pressure of water from the total pressure of the moist gas which contains water vapours also.

$P_{moist gas} = P_{dry gas} + P_{water vapour}$

The pressure exerted by water vapour is known as aqueous tension.

$2 .$ Determination of total pressure-

This law is used to determine the total pressure exerted by a mixture of chemically non- reacting gases. And the total pressure is the sum of partial pressures of individual gases as given in the equation $(i)$ .

State and explain Dalton’s law of partial pressure. What are its applications ?

Important Questions on States of Matter : Gases and Liquids

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