PLEASE explain steps, having troble solving these two questions 1. a) What are t

Question

PLEASE explain steps, having troble solving these two questions

1. a) What are the partial and total pressures of a solution obtained by mixing 35.8 g benzene, C6H6, and 56.7 g toluene, C7H8, at 25.0 degerees Celsius?

b) Determine the composition of the vapor above this benzene-toluene solution. At 25.0 degerees Celsius the vapor pressures of benzene and toluene are 95.1 mm Hg and 28.4 mm Hg respectively.

2. Claculate the mole fraction of benzene in a benzene-toluene solution that is in equilibrium at 25.0 degrees Celsius with a vapor phase that contains 62.0 mol % C6H6. At 25.0 degrees Celsius the vapor pressures of benzene and toluene are 95.1 mm Hg and 28.4 mm Hg respectively.

Explanation / Answer

Moles of benzene = mass/molar mass

= 35.8/78.11 = 0.4583 mol

Moles of toluene = mass/molar mass

= 56.7/92.14 = 0.6154 mol

Mole fraction of benzene in liquid phase = moles of benzene/(moles of benzene + moles of toluene)

= 0.4583/(0.4583 + 0.6154) = 0.427

Partial pressure of benzene = mole fraction of benzene in liquid phase x vapor pressure of benzene

= 0.427 x 95.1 = 40.6 Torr

Partial pressure of toluene = mole fraction of toluene in liquid phase x vapor pressure of toluene

= (1 - 0.427) x 28.4 = 16.3 Torr

Mole fraction of benzene in vapor phase = partial pressure of benzene/(partial pressure of benzene + partial pressure of toluene)

= 40.6/(40.6 + 16.3) = 0.714

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