Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The parial  vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46g of toluene in torr is

  • Option 1)

    50

  • Option 2)

    25

  • Option 3)

    37.5

  • Option 4)

    53.5

 

Answers (2)
A Abarna

option 1

V Vakul

As we learned

 

Raoult's Law -

The partial pressure of any volatile constituents of a solution at a given temperature is equal to the product of vapour pressure of pure constituent and its mole fraction in the solution.

P_{A}=P_{A}^{0}x_{A}

P_{B}=P_{B}^{0}x_{B}

 

 

- wherein

P_{A}^{0}  and P_{B}^{0} are vapour pressures of pure liquids.

P_{A}  and P_{B} are vapour pressures of A and B respectively.

 

 P_{B}=P_{B}^{0}X_{B};    \therefore P_{B}=\frac{\frac{78}{78}}{\frac{78}{78}+\frac{46}{92}}\times 75;   \therefore P_{B}=50 torr


Option 1)

50

Option 2)

25

Option 3)

37.5

Option 4)

53.5

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