Which of the following statements about the composition of the vapour over an ideal 1: 1 molar mixture of benzene and toluene is correct ? Assume that the temperature is constant at 25° C. (Given, Vapour Pressure Data at 25° C, benzene = 12.8 kPa, toluene = 3.85 kPa)

Question

Which of the following statements about the composition of the vapour over an ideal 1: 1 molar mixture of benzene and toluene is correct ? Assume that the temperature is constant at 25° C. (Given, Vapour Pressure Data at 25° C, benzene = 12.8 kPa, toluene = 3.85 kPa) (A) The vapour will contain a higher percentage of toluene (B) The vapour will contain equal amounts of benzene and toluene (C) Not enough information is given to make a prediction (D) The vapour will contain a higher percentage of benzene

Tardigrade Admin · Accepted Answer

V.P of C6 H6 > V.P of C6 H5 CH3 ∵ YA = (P°A XA/P) , YB = (P°B XB/P) XA and XB are same so mole fraction in vapour phase is directly proportional to the vapour pressure.

Q. Which of the following statements about the composition of the vapour over an ideal 1:1 molar mixture of benzene and toluene is correct ? Assume that the temperature is constant at 25∘C. (Given, Vapour Pressure Data at 25∘C, benzene = 12.8kPa, toluene = 3.85kPa)

The vapour will contain a higher percentage of toluene

The vapour will contain equal amounts of benzene and toluene

Not enough information is given to make a prediction

The vapour will contain a higher percentage of benzene

V.P of C6​H6​> V.P of C6​H5​CH3​ ∵YA​=PPA∘​XA​​,YB​=PPB∘​XB​​ XA​ and XB​ are same so mole fraction in vapour phase is directly proportional to the vapour pressure.

V.P of $C_{6} H_{6} >$ V.P of $C_{6} H_{5} C H_{3}$
$∵ Y_{A} = \frac{P _{A}^{\circ} X _{A}}{P}, Y_{B} = \frac{P _{B}^{\circ} X _{B}}{P}$
$X_{A}$ and $X_{B}$ are same so mole fraction in vapour phase is directly proportional to the vapour pressure.