How Does Dew Point Change in a Gas Mixture of Different Proportions?

In summary, the conversation discusses the process of condensation in gases and how it applies to gas mixtures. Raoults law is mentioned, which states that at equilibrium, the vapor and liquid mole fractions are proportional to each other. The minimum pressure required for condensation to occur in a gas mixture is also calculated.
  • #1
Pash
1
0
Dear All...
For my first post in this forum I have choosen an easy question for you all!

If I have a gas at room temperature and I start to compress it, when the gas reach its dew point, condensation starts

What about for a gas mixture?? I try to be clear!

I have two real gasses: A & B.
At room temperature the gas A condenses at 10bar, the gas B at 100bar.

What happens if I start to compress a mixture of 50% of gas A and 50% of gas B?

And if I change the mixture?? for example 20%-80% or 80%-20% of gas A-B respectively?

At the present I was not able to understand if this is an easy question with very difficul application or directly a difficult question!

Thanks!
 
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  • #2
Raoults law says that, when vapor and liquid are at equilibrium $$P^*x=py$$ for each species, where P* is the equilibrium vapor pressure at the temperature, x is the mole fraction in the liquid, y is the mole fraction in the vapor, and p is the total pressure. So, a bicomponent mixture of A and B at vapor-liquid equilibrium, $$x_A=\frac{py_A}{P^*_A}$$and $$x_B=\frac{py_B}{P^*_B}$$At the condensation point, the pressure p must be high enough for the mole fractions in the liquid to add up to 1: $$x_A+x_B=\frac{py_A}{P^*_A}+\frac{py_B}{P^*_B}=1$$So, the minimum pressure required for condensation to begin is $$p=\frac{1}{\left[\frac{y_A}{P^*_A}+\frac{y_B}{P^*_B}\right]}$$
 

1. What is the dew point of a gas mixture?

The dew point of a gas mixture is the temperature at which the gas will reach saturation and water vapor will start to condense into liquid form.

2. How is the dew point of a gas mixture calculated?

The dew point of a gas mixture is calculated by using the partial pressures of the individual components in the gas mixture and their respective vapor pressure curves.

3. Why is the dew point of a gas mixture important?

The dew point of a gas mixture is important because it can affect the performance of certain processes, such as gas separation and purification, and can also impact the quality of the end product in industries such as food and pharmaceuticals.

4. How does the dew point of a gas mixture change with temperature and pressure?

The dew point of a gas mixture decreases with decreasing temperature and increasing pressure. This is because at lower temperatures and higher pressures, the gas mixture is less likely to reach saturation and condensation will occur at a lower dew point.

5. Can the dew point of a gas mixture be controlled?

Yes, the dew point of a gas mixture can be controlled by adjusting the temperature and pressure of the gas mixture, as well as by using methods such as drying or humidification to remove or add water vapor from the mixture.

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