A solution is made by mixing 32.0 mL of ethanol, C2H6O, and 68.0 mL of water. As

Question

A solution is made by mixing 32.0 mL of ethanol, C2H6O, and 68.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20°C?

Periodic Table Sapling Learning A solution is made by mixing 320 mL of ethanol, CHO, and 680 mL of water behavior, what is the vapor pressure of the solution at 20 Assurming ideal Values at 20 Liquid ethanol 0.789 water 0.998 Tom) 43.9 2.22 To rr 17.5 Previous ®Gue Up & View Scition #Try Agan ONext Each volatile component contributes to the vapor pressure of the solution, Peknoe PA and Ps'are the vapor pressures of the where XA and Xg are the mole fractions of the components and pure components

Explanation / Answer

Answer:

Given volume of ethanol=32 ml and density=0.789 g/ml

Density=mass/volume

Mass of ethanol = 0.789 g/ml x 32 ml =25.248 g.

Molar mass of ethanol= 46 g/mol
Moles ethanol = mass/molar mass=25.248 g/46 g/mole = 0.548 moles.

Given volume of water=68 ml and density=0.998 g/ml

Mass of water=density x volume=0.998 g/ml x 68 ml=67.864g.

Molar mass of water=18 g/mol

Moles water =67.864 g/18 g/mole = 3.77 moles
total moles = 0.548 mol+ 3.77 mol= 4.318 moles

Mole fraction ethanol = mol of ethanol/total moles

=0.548 mol/4.318 mol=0.127.

Moles fraction water = 3.77 mol/4.318 mol = 0.873.

Given vapour pressure of ethanol=43.9 torr and water=17.5 torr.

Partial pressure of ethanol = mole fraction ethanol x vapor pressure ethanol= 0.127 x 43.9 torr=5.575 torr
partial pressure water =0.873x17.5 torr = 15.277 torr.
Total vapor pressure over solution =5.575 torr + 15.277 torr

Total vapour pressure= 20.85 torr.

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