Discussion on methanol and water
Thread Content
I have a few questions for everyone. First: under the same pressure and temperature, is the latent heat of condensation for water vapor much smaller than that of methanol vapor? ? Are there any data for comparison? ? II: At the same temperature and volume, is the pressure of pure methanol vapor higher than that of a mixture of methanol vapor and water vapor? ? ? Could you explain it? ? ? III: Under the same pressure, is water vapor more easily condensed than methanol vapor? ? ? ? Request for an explanation of the principle
1. The boiling point of water is 100 degrees, while that of methanol is only 65 degrees; it’s clear then that the intermolecular forces between water molecules are stronger than those in methanol. Therefore, the heat released during condensation should be greater for water vapor. 2. Do you mean in a vacuum container, which has a higher vapor pressure, methanol or a methanol/water solution? These two substances do not have an azeotrope, and methanol has a relatively low boiling point; therefore, the vapor pressure is higher when there is more methanol, resulting in higher pressure inside the container. 3. Are the temperatures the same? At the same temperature, the vapor pressure of water is lower than that of methanol; therefore, more gas-phase molecules should condense into the liquid phase!
Agree with the first and second points mentioned by the person above. Thirdly, I believe the conditions stated are not accurate; since the voltage division is the same, the temperatures cannot be identical, so the explanation for the third point is clearly incorrect. Personally, I think what the original poster is trying to ask is which component – methanol or water – will condense more easily under the same pressure and at the same temperature. If that’s what is meant, the situation is rather complex, as the latent heat of vaporization of water is greater than that of methanol. A specific temperature needs to be determined for the calculation; I haven’t checked the data, and perhaps different temperatures will yield different results. However, according to the Antoine equation, methanol generally condenses more easily under the same conditions. http://bbs.hcbbs.com/thread-521334-1-1.html This post contains the calculation method for condensate volume.
First, thank my friend for the answer. To supplement the first point, I’m referring to pure methanol vapor and a mixture of methanol and water vapor. At the same temperature, does pure methanol vapor release more heat? ? ? ? Thirdly, I agree quite a bit with the view from the second floor. Because in distillation, if water enters the top of an atmospheric pressure column, it is relatively easy for negative pressure to occur. As for pure methanol vapor, pressure can be correlated with temperature. Rather than high temperature and low pressure.