Question

state and explain Dalton's law of partial pressure.​

Answer 1

Answer:

Dalton's law of partial pressure states:

'the total pressure of a mixture of gases occupying a given volume is equal to the sum of the pressures of each gas, considered separately, at constant temperature'.

Answer 2

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• Partial pressure: Pressure exerted by the individual gases in a mixture

• Statement: At constant temperature, the total pressure exerted by a mixture of two or more non-reacting gases, enclosed in a definite volume, is equal to the sum of the partial pressures of the individual gases.

Mathematically,.

P(total) = p1 + p2 + p3 + ……….. (At constant T and V)

Where, ptotal = Total pressure exerted by the mixture

p1 + p2 + p3, ... = Partial pressures of the individual gases

Partial pressure in term of mole fraction:

Let,

A mixture is made of two gases 1 and 2.

mole fraction of one gas = χ1 = n1/ n = n1/ (n1 + n2 )................. (1)

where, n1 is number of moles of gas a, n2 is the number of moles of gas 2 and n is total number of mole of all gases in the mixture

Using ideal gas equation,

p1 = n1RT/V and p2 = n2RT/V.................... (2)

So, total pressure of mixture

Pt = p1 + p2

Pt = (n1 + n2 ) RT/V............................(3)

Divide (2) by (3)

p1/ Pt = n1/ (n1 + n2 )

From (1)

p1/ Pt = χ1

Thus,

The partial pressure of a gas in a mixture = mole fraction of gas × total pressure of the mixture.