ChemE: vapor pressure and condensation

In summary, at the equilibrium temperature, 0.194 mol fraction of CCl4 liquid is formed and 0.814 mol fraction of CCl4 remains in the gas phase. The total number of moles remaining in the gas phase is 1.915 mol. The mole fraction of CCl4 in the gas phase is 0.796.
  • #1
GreatEscapist
180
0

Homework Statement


A gaseous mixture containing 0.190 mol fraction of carbon tetrachloride (CCl4) and 0.810 mol fraction of dry air is initially at 62.0°C and 1141 mmHg. If this mixture is cooled at a constant pressure, at what temperature does the CCl4 first start to condense? I already did this problem

At what temperature would 56.0% of the CCl4 condense?

Homework Equations


Partial pressure = p*(T)
log10(p*)= A + (B/(T+C))
I'm sure there are more I'm supposed to use

The Attempt at a Solution



After solving for the original problem, for the second, I know that I need to find how many moles are condensed...but I don't know how to do that. Or what to do after that, or with that information.
 
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  • #2
Not sure how the dry air enters the problem, but disregarding that, once the CCl4 starts to condense, it is impossible to further reduce the temperature of the (two) CCl4 phases at constant pressure until the CCl4 is saturated liquid. That should answer your question ...
 
  • #3
GreatEscapist said:

Homework Statement


A gaseous mixture containing 0.190 mol fraction of carbon tetrachloride (CCl4) and 0.810 mol fraction of dry air is initially at 62.0°C and 1141 mmHg. If this mixture is cooled at a constant pressure, at what temperature does the CCl4 first start to condense? I already did this problem

At what temperature would 56.0% of the CCl4 condense?

Homework Equations


Partial pressure = p*(T)
log10(p*)= A + (B/(T+C))
I'm sure there are more I'm supposed to use

The Attempt at a Solution



After solving for the original problem, for the second, I know that I need to find how many moles are condensed...but I don't know how to do that. Or what to do after that, or with that information.

Take as a basis one mole of gas. Then the number of moles of CCl4 is 0.19, and the number of moles of air is 0.81. If 56% of the CCl4 condenses, how many moles of CCl4 liquid is formed, and how many moles of CCl4 remain in the gas phase? What is the total number of moles remaining in the gas phase (air plus CCl4)? At that point, what is the mole fraction of CCl4 in the gas phase? Since the total pressure remains 1141 mm Hg, what is the partial pressure of CCl4 in the gas phase? What is the equilibrium temperature at this vapor pressure of CCl4?
 

1. What is vapor pressure?

Vapor pressure is the pressure exerted by a vapor above its liquid or solid form in a closed container at a given temperature. It is a measure of the tendency of a substance to escape from its liquid or solid form and enter the gas phase.

2. How is vapor pressure related to temperature?

Vapor pressure increases with an increase in temperature. This is because higher temperatures provide more energy to the particles of a substance, allowing them to overcome the attractive forces of the liquid or solid and enter the gas phase more easily.

3. What is the relationship between vapor pressure and boiling point?

As vapor pressure increases, so does the boiling point. This is because at higher vapor pressures, the vapor pressure of a substance is equal to the atmospheric pressure, which is the condition required for boiling to occur.

4. How does vapor pressure affect condensation?

Vapor pressure plays a crucial role in the process of condensation. When the vapor pressure of a substance is equal to or greater than the atmospheric pressure, the substance will condense from a gas to a liquid. This is why condensation occurs when warm, moist air encounters cooler surfaces or temperatures.

5. Can vapor pressure be manipulated?

Yes, vapor pressure can be manipulated through changes in temperature or pressure. Lowering the temperature or increasing the pressure can decrease the vapor pressure, while raising the temperature or decreasing the pressure can increase the vapor pressure.

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