JEE Main2010ChemistrySolutionsActual
On mixing, heptane and octane form an ideal solution. At 373 ~K , the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0 ~g of heptane and 35 ~g of octane will be (molar mass of heptane =100 ~g ~mol ⁻¹ an dof octane =114 ~g ~mol ⁻¹ ).
Options
- A72.0 kPa
- B36.1 kPa
- C96.2 kPa
- D144.5 kPa
Correct answer
A. 72.0 kPa
Step-by-step solution
Mole fraction of Heptane = 25 / 100 25 100 + 35 114 = 0.25 0.557 =0.45 X _ Hep tane =0.45 . Mole fraction of octane =0.55= X _ octane Total pressure = X_i P_i^0=(105 0.45)+(45 0.55) kP _ a =72.0 KPa