Question

Answer 13th question correctly and get 15 points
A mixture of benzene and toluene contains 30% by mass of toluene at 30 degree celcius by vapour pressure of pure toulene 36.7 mm of hg and that of pure benzene is 118.2 mm of hg.assuming that two liquids form ideal solutions ,calculate the total pressure and partial pressure of each constituent above the solution at 30degree celcius

Answer 1

A solution is defined as a:

A .

Homogeneous mixture of two or more substances

B .

Heterogeneous mixture of two or more substances

C .

Homogeneous mixture of liquid and solid components only

D .

Homogeneous mixture consisting of water as one of the components.

A solution is a homogeneous mixture of two or more substances. A solution may exist in any phase. 

A solution consists of a solute and a solvent. 

The solute is the substance that is dissolved in the solvent.

For example, in a saline solution, salt is the solute dissolved in water as the solvent.

Answer 2

Given:

Mass % of toluene = 30%

Vapour pressure of pure toluene, Pt° = 36.7 mm Hg

Vapour pressure of pure benzene, Pb° = 118.2 mm Hg

To Find:

The total pressure and partial pressure of each constituent.

Calculation:

Let the total mass be x

⇒ Mass of toluene = 0.3 x

⇒ Mass of benzene = 0.7 x

- Mole fraction of toluene Xt = (0.3x/92) / {(0.3x/92) + (0.7x/78)}

⇒ Xt = 0.266

- Mole fraction of benzene Xb = 1 - 0.266 = 0.734

- Partial pressure of toluene, Pt = Pt° × Xt

⇒ Pt = 36.7 × 0.266

⇒ Pt = 9.76 mm Hg

- Partial pressure of benzene, Pb = Pb° × Xb

⇒ Pb = 118.2 × 0.734

⇒ Pb = 86.76 mm Hg

- Total Pressure P = Pt + Pb

⇒ P = 9.76 + 86.76

⇒ P = 96.52 mm Hg

- So the partial pressure of toluene is 9.76 mm Hg, the partial pressure of benzene is 86.76 mm Hg and the total pressure is 96.52 mm Hg.