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20. Which statement below regarding vapor pressure is not correct? a. Vapor pres

ID: 845578 • Letter: 2

Question

20. Which statement below regarding vapor pressure is not correct?

a.

Vapor pressure is an intensive property.

b.

The substance with the stronger intermolecular forces has the lower vapor pressure.

c.

Vapor pressure increases with increasing temperature.

d.

Pure water has a higher vapor pressure at a given temperature than seawater.

e.

A nonvolatile solute increases the vapor pressure of the solvent.

21. A solution is prepared by adding 1.50 mol glucose, which is not volatile, to 3.50 mol water. What is the vapor pressure of this solution at 25

a.

Vapor pressure is an intensive property.

b.

The substance with the stronger intermolecular forces has the lower vapor pressure.

c.

Vapor pressure increases with increasing temperature.

d.

Pure water has a higher vapor pressure at a given temperature than seawater.

e.

A nonvolatile solute increases the vapor pressure of the solvent.

Explanation / Answer

1] A nonvolatile solute increases the vapor pressure of the solvent.A nonvolatile solute increases the vapor pressure of the solvent.

2]vapour pressure of this solution =

moles total = 3.5+1.5 = 5.0 moles

so vaour pressure = 3/10 *0 + 7/10 * 23.8

= 16.7 torr

3] same as above (process)

= P= 4.5/4.8 * 23.8

= 22.3 torr

4]total moles = 6.5+0.3+0.2 = 7

so pressure = 6.5 * 42.2 /7

5]find the moles of the two components

than find the mole fraction of both the components

than follow the step = P = mole fraction of methanol * its vapour pressure + moles fraction of ethanol * its vapour pressure

6]same as 5

7 ] molality = 0.755 / 1.75

8]moles = molality * mass

= 50* 0.155

9]for osmotic pressure use

P = cRT

for depression in freezing point use

delta T = Kf * molality