Question

What will be the partial pressure of h2 in a flask containing 2g of h2,14g of n2 and16g of o2?

Answer 1

We know,

No.of moles of a substance=Amt. of substance(in g)/Mwt. of that substance

Here,

Mwt of H2=2 u

Mwt of N2=14*2=28 u

Mwt of O2=16*2=32 u

=> No. of moles of:-

• H2=2/2=1 mole
• N2=14/28=0.5 mole
• O2=16/32=0.5 mole

We know, according to Dalton's Law of Partial Pressures

"In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases."

And the partial pressure of each gas is directly proportional to its mole fraction in the mixture.

Assuming total pressure as P (not given in the question),

Partial Pressure of H2=1*P/(1+0.5+0.5)

                                    =P/2

Ans-P/2

Answer 2

Given:

A flask contains 2g of h2,14g of n2 and16g of o2.

To Find:

The partial pressure of h2.

Solution:

WKT:

• Number of moles of a substance = Amount of substance(in g)/Molecular weight of that substance(in g).

Here,

Mol.wt of H2=2u

Mol.wt of N2=28u

Mol.wt of O2=32u

=> No. of moles of:-

H2=2/2=1 mole

N2=14/28=0.5 mole

O2=16/32=0.5 mole

According to Dalton's Law of Partial Pressures:

• "In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases."

• And the partial pressure of each gas is directly proportional to its mole fraction in the mixture.

Assuming total pressure as 'P'.

Partial Pressure of H2=1*P/(1+0.5+0.5) = P/2

                                   

Hence, the partial pressure of H2 is P/2.

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