# Tagged Questions

44 views

### Does stew lose more liquid if stirred as it cools?

Suppose I cook a stew or soup and then take it off of the stove and leave it uncovered to cool. Of course, it will cool faster if I stir it (more surface area), but it will, eventually, cool to room ...
65 views

### Does the temperature of water determine how much heat will be removed from air used to evaporate it?

This is a question about evaporative cooling as used in residential evaporative cooling appliances. This type of cooling uses the heat in the ambient outside air to evaporate water and remove the heat ...
97 views

### Can water evaporate when frozen?

If an ice cube is stored in a freezer could it evaporate given enough time? Is there a temperature below which water cannot evaporate (even just a little)?
379 views

### Why does a water drop on a hot plate at $150^o C$ evaporate faster than on a plate at $200^o C$?

I recently read that: "A drop of water landing on a hot plate at $150^o C \:(300 F)$ evaporates in a few seconds. A drop of water landing on a hot plate at $200^o C \:(400 F)$ survives a whole ...
6k views

### Does wrapping a wet paper towel around a glass bottle really speed up the cooling process?

There are claims like this one that you can improve the cooling speed of beverages when you put them wrapped in a wet paper towel inside the refrigerator/freezer. I've just tried it by myself and ...
20 views

### Time for which a drop stays in the leidenfrost point

Is there any way to find out the time required for a drop of given dimensions to vaporize after attaining Leidenfrost point?
829 views

### Why doesn't breath condense around poop of flies on the window's glass?

One day it was raining outside and I was breathing on the glass of my window. I noticed that around the spots of fly poop there is a circle where vapor does not condense. With time the circle becomes ...
234 views

### Auto-refrigeration

I'm reading about the auto-refrigeration effect and can't find a really good explanation. Is the idea that when you have your condensed liquid, and then release it into a low pressure environment, ...
391 views

### Does evaporation decrease entropy?

I have a container of water in thermal equilibrium (there are no temperature fluctuations inside the container). Some molecules will evaporate out of the container of water thus decreasing its ...
125 views

### Is vapour pressure based on partial pressures or just total pressure on the liquid?

The explanation for the boiling point of water is that at 100C, the vapour pressure becomes greater than atmospheric pressure. But say you had a a jar of water sealed in argon at 1atm, which is larger ...
180 views

### Does coffee with cream cool slower than black coffee?

At Modernist Cuisine, Nathan Myhrvold states that "Coffee with cream cools about 20% slower than black coffee". He then gives three reasons, two of them related to radiation and the third one to the ...
128 views

### How do you keep a fridge full of food cooler?

I just graduated and a mate moved into a flat (none of us are physicists by the way). So, were graduates, we got a new flat, and were broke. So, were now having a debate on how to keep a fridge ...
116 views

### Can you confirm 2 simple statements about vaporization?

Vaporization is an interesting engineering subject, but unfortunately much about it has always been unclear to me. Recent research of mine has brought my mind to link vapor pressure to boiling and ...
357 views

### Liquid nitrogen condensing oxygen out of the air

In this video, a pool of liquid nitrogen in a metal bowl can cool it enough so that oxygen from the air condenses at the bottom: ...
348 views

### Does coffee cool faster than tap water?

A friend of mine, based on casual observation, believes that coffee will cool faster than ordinary hot tap water. Being curious about this I have tried to investigate it myself, but I'm not well ...
200 views

### What limits the mass transfer from a boiler to a condenser in a sealed vessel?

If we set up an evacuated vessel where we keep one end at a higher temperature than the other, and then introduce a liquid at the warm end, it will evaporate and condense at the cooler end. If we trap ...
5k views

### Thermodynamics: Are pressure and temperature enough to calculate enthalpy?

From the chart above, it looks like it is possible to calculate enthalpy from just pressure and temperature. After a few hours of Googling my question, I'm not able to find anything helpful. My ...
419 views

### Would a small puddle of water evaporate faster if you spread a dry towel over it?

Let's say you spill 10ml of water on the kitchen counter. It forms a small puddle that would evaporate after a while (assuming room temperature and sane humidity). Would spreading a large, dry towel ...
132 views

### Conditions for heat exchange and evaporation

I wonder if there is any law for heat exchange. I have learnt that heat exchange between systems occurs when the temperature of respective systems differ. But in case of evaporation, the process ...
6k views

### How does an earthen pot keep water cool?

I understand that evaporative cooling takes place thanks to small pores contained in the pot and that allow some water to go through and evaporate. However I couldn't understand clearly whether water ...
120 views

### Will humid air mitigate airborn dust due to neutralization of static electricity?

I have came to understand that humid air will help prevent electrostatic forces that can propel dust and cause it to cling to surfaces. My first question: is this above statement true? If the answer ...
1k views

### Why can't I evaporate water without wind, just heat? (not boiling,evaporating!) Or can I?

So here is the thing, I searched all over the internet for this but all the sources say that I need wind because the process of evaporation goes as follow: Water particles at the top layer with ...
396 views

### Time to establish saturated vapour pressure above liquid

Thought experiment - a liquid is in a closed container in equilibrium with its vapour, and then suddenly all the vapour is pumped away. Switch off the pump so that instantaneosuly there is no vapour ...
1k views

### Heat of vaporization of water - dependence on relative humidity?

Does the heat of vaporization of water depend strongly on the relative humidity of the gas into which it evaporates? Some context: If we want to calculate the dew point of water, we find the ...
4k views

### How to calculate the evaporative cooling rate needed to protect a house from forest fire

Recently in our area there has been a large forest fire and I've been looking into home defense from such things. I am not a physicist - but can do some basic math. I was wondering how I could ...