Questions tagged [evaporation]
The process of a liquid changing to a gaseous state
363
questions
0
votes
1
answer
29
views
Does gas pressure impact the rate of evaporation?
As we know, evaporation occurs when a liquid molecule has a kinetic energy that is greater than the minimum amount of energy needed to overcome the intermolecular attractive forces holding it in the ...
- 3
0
votes
0
answers
20
views
6-cycle with steam injection [closed]
I have been doing some engine research and have a question about the Crower 6-stroke engine. In this engine, after the 4th cycle, water is injected into the cylinder. The claim is that this would ...
0
votes
1
answer
28
views
Why water vapor condenses on glass? [closed]
I've read an answer to this question that stated glass was colder than air, causing this transfer of energy from the vapor to the glass, creating this condensation. But why is the glass colder than ...
0
votes
0
answers
30
views
Why do we feel cool after switching fan? [duplicate]
Please see that my actual question is not similar to this: Why do we feel cool when we turn our fans on?
Suppose I switched my fan on. The air particles start moving. Since, their kinetic energy ...
- 71
0
votes
0
answers
24
views
Can oil "boil" in vacuum ? (Is it usable to make absolute (low) pressure measurement ?)
In order to measure vacuum absolute pressure, I thought about making a water column barometer, however, water will boil under high vacuum. Can I use oil instead ? On one side, I would expect any ...
- 503
3
votes
1
answer
60
views
Does a metal evaporate as single atoms or as molecules?
If I had a liquid metal, like Al, and I begin heating it so it evaporates, would the evaporating Al be in the form of atoms or as molecules?
- 83
1
vote
0
answers
20
views
When water is evaporated and the particles with a little more energy breaks away, Why do the molecules left have less motion?
From Feynman's Six easy pieces:
Then a molecule leaves it is due to an accidental, extra accumulation of a little bit more than ordinary energy, which it needs if it is to break away from the ...
- 21
0
votes
1
answer
61
views
Why saturated vapor does not obey gas laws? [duplicate]
in my book it has mentioned "number of saturate molecules does not remain constant when the temperature changes(mass of vapor is not constant),therefor saturated vapor does not obeys gas law"...
- 11
0
votes
0
answers
27
views
Non-Equillibrium thermodynamics in rapid evaporation of liquid by laser heating in vacuum chamber
I currently have some results that I am trying to understand. These results show the peak temperature of a crucible (w/ a 10mm diameter) filled with liquid Ag (see diagram). The surface of the liquid ...
- 83
1
vote
1
answer
27
views
Steam Produced by Induction Cookers
I had recently noticed that induction cookers produce much more steam than normal gas tops and when I set the setting in the induction cooker to 'steam' it produces ever more steam. I used the same ...
0
votes
0
answers
29
views
Effect of the temperature dependence of $\Delta H_{vap}$ on the vapor pressure?
I am aware that the enthalpy of vaporization of a fluid ,$\Delta H_{vap}$ is temperature dependent since it must be equal to zero at the critical temperature of said fluid, $T_c$ (although this is ...
- 83
0
votes
0
answers
20
views
feeling humidity - absolute vs relative
I m trying to understand whether it is absolute humidity (how much moisture in the air) or relative humidity (percentage to total saturation) reflects how humid we feel. In most places i searched the ...
- 113
0
votes
1
answer
18
views
Convection from rapidly evaporating liquid inside vacuum chamber?
If we have a liquid that is is being actively heated and is rapidly evaporating (let's say around 1g/s for Ag at 1500K) inside a vacuum chamber, can convection around the liquid/vapor interface occur ...
- 83
1
vote
0
answers
41
views
What causes the rim of the droplet to stop moving in the Marangoni effect?
This is specifically concerning a set-up where a droplet containing a mixture of water and alcohol is deposited on the surface of vegetable oil in a petri dish. I want to know what causes the inner ...
- 21
0
votes
1
answer
45
views
Mystifying Relative Humidity - That can't be accurate?
While humidifying a room in my home, measuring the Temperature and Relative Humidity (T&RH respectively) every 8 hours, I noticed that RH rises and falls with T when it should be the inverse.
I ...
- 101
1
vote
0
answers
28
views
How do I correlate the Rayleigh-Taylor instability with this Marangoni Bursting phenomenon?
The droplet was a water-isopropanol mixture of concentration 50% and was deposited on a 5mm thick layer of sunflower oil in a petri dish.
- 21
0
votes
0
answers
75
views
Why is the latent heat of vaporization 0 at the critical point?
This is not a homework question.
The critical point of water is $\mathrm{374 \ C}$ and $\mathrm{22.06 \ MPa}$. At the critical point the latent heat of vaporization is $0$ - why?
Assume the water ...
1
vote
0
answers
56
views
How much heat energy is required to bring 1 liter of water to the critical point?
This is not a homework question.
The critical point of water is 374 C and 22.06 MPa. At the critical point the latent heat of vaporization is 0 - why?
Assume the water starts at 100 C.
If you add the ...
0
votes
1
answer
44
views
Why my glass spects or windows becone blurr in winter i.e cold weather due to my breath but NOT in summer i.e hot weather?and why disappear after?
I noticed than when I blow up on my spects it get blurr as water vapor condense onmy spects, but after some time it dissappear! How?
If water vapor at first place loose heat to my spects as my spects ...
0
votes
2
answers
46
views
Why we spread clothes for fast drying and how evaporation rate become faster then?
Why wrinkled cloth (not spread out) takes time to dry up
Look at diagram
Here, water molecule on surface of wrinkled area will also evaporate same as non wrinkled area (may be) ! So why it takes time ...
0
votes
1
answer
39
views
Does the dew point of a certain amount of vapor in a confined space change with temperature?
I know that dew point is temperature independent and is pressure dependent.But my textbook states that in a confined space dew point changes with temperature as the volume is constant pressure is ...
- 558
0
votes
0
answers
44
views
In the Hertz-Knudsen Equation, why does increasing the temperature decrease the evaporation rate?
Currently I am trying to understand the form of the Hertz-Knudsen equation, describing the evaporation rate (number of particles per unit time per unit area) from a liquid:
$\frac{1}{A}\frac{dN}{dt}$ =...
- 83
0
votes
1
answer
81
views
When you reduce the pressure of a liquid below it's saturation pressure within a container, does it boil or evaporate? [closed]
I was playing around with a compressed air can, and it made me think of the greater physics behind what actually happens when I pull the trigger.
I know that compressed "air" cans actually ...
1
vote
1
answer
33
views
Equation for enegy loss from evaporation/sublimation in vacuum?
Imagine you have a solid that you are rapidly heating inside a vacuum chamber with some kind of thermal heater or a laser such that the material begins to evaporate or sublimate. Obviously radiative ...
- 83
0
votes
0
answers
8
views
Does having a large liquid surface effect evaporation stability?
Imagine I have a metal block in a vacuum chamber, which is then heated by a laser. It is heated past its melting point until a small melt pool is present at the location of the laser.
My question is: ...
- 83
0
votes
0
answers
25
views
What is the rationale-intuition for the "constant flux layer assumption", in atmospheric surface layer for turbent "diffusion"?
I wonder if, beyond the math, there is a physical intuition that I'm missing underlying this ubiquitous assumption of vertical constant fluxes in the surface layer (particularly in the inertial ...
- 101
0
votes
1
answer
44
views
If saturated vapor does not obey ideal gas laws then how is mass of the saturated vapor proportional to the saturated vapor pressure?
My textbook mentions that unsaturated vapor obeys ideal gas law but saturated vapor does not. I could understand that air/vapor are not ideal so they won't obey ideal gas laws. But how can unsaturated ...
- 558
0
votes
0
answers
12
views
Evaporation rate as a function of initial volume? [duplicate]
I had done some cursory digging online and found that at my elevation the boil evaporation loss was about 14% per hour. So to test this out I boiled 3785mL (1 gallon) of water for an hour on my ...
- 101
1
vote
1
answer
39
views
How do I calculate rate of water evaporation at various water temps?
I am trying to figure out how many gallons of fresh water will evaporate per hour in a large tank at various water temperatures?
Specifically,
surface area is 250,000 sq ft surface area (500' x 500')
...
- 13
1
vote
1
answer
51
views
Does the half filled water bottle pressure increase as more water from water evaporate into that empty space until that space become 100% humid?
When we kept a half empty bottle and half filled with water, and the air in bottle is not fully saturated of water vapor.
So we know that bottle from water will evaporate until the space in bottle is ...
user313211
-1
votes
2
answers
56
views
What contaminant materials should be avoided for reaching ultra-high vacuum? [closed]
This question relates to ultra-high vacuum chambers (order of ~$10^{-10}$ mbar) in experimental setups.
For this particular vacuum chamber, we have a set of ion pumps and a turbomolecular pump (...
- 3
-1
votes
1
answer
47
views
Does temperature in a vessel with same top surface area as a earthern pot and same amount of water have same temperature of water?
Many people answer the question 'why earthern pot keep water cool?' In this way
'Because it has large surface area that allow more evaporation than other vessels we used to keep, so more cooling.'
But,...
user315475
1
vote
1
answer
63
views
Black holes and Hawking radiation
If Hawking radiation comes from outside the event horizon, how will it make the black hole evaporate? Also, how can the radiation be related to a blackhole's mass if it's coming from somewhere outside ...
- 11
0
votes
3
answers
48
views
Why water in earthern pot cools only upto some extent?
I have noticed that water cools in matka(earthern pot) and people give it as a reason of evaporation of water at pot surface and further conduction of heat of water to cool down pot.
But evaporation ...
user315475
0
votes
2
answers
171
views
Why pouring sanitizer on hand feel much cooler than water although both perform evaporation?
Which absorb more heat from hand?
Sanitizer or Water?
Both absorb heat from hand than why pouring sanitizer on hand make hand feel much cooler than rhat of water?
user315475
1
vote
1
answer
60
views
Why we need earthern pot to keep water cold although open surrounding also allow evaporation!
Why earthern pot keep water cold?
Many answers say it allow evaporation through pores, but evaporation can happen without pot too, in open surrounding!
So why specifically we need earthern pot?
user315475
0
votes
0
answers
98
views
Can silicone oil evaporate at an appreciable rate at low pressures?
Under normal conditions of ambient temperature and pressure, evaporation of silicone oils is so slow that it can be neglected, because the vapour pressure of the oil is typically of the order of ...
- 750
0
votes
0
answers
26
views
Why does this device need an evacuated chamber to function?
I have come across an interesting paper about generating power from a difference in salinity between two solutions. It describes a device where reservoirs of high and low salinity water are connected ...
0
votes
0
answers
26
views
Does increasing dynamic pressure of moist air increase condensation?
In a pressure cooker, increasing static pressure causes evaporation of water to be less thermodynamically favorable, and increases the rate of condensation of water. This is because water molecules ...
1
vote
0
answers
27
views
Vapor Pressure in Heated Pressure Vessel
This question is a bit complex, so thanks in advance for addressing it!
I'm working on a reaction vessel that heats a water solution to 95°C to perform chemical reactions. The design is a ...
- 11
0
votes
2
answers
390
views
Does it take more energy to evaporate a litre of water in a vacuum, and if so, why?
I got this information and want to know if it is correct and if so, why does it take more energy to evaporate water in a vacuum compared to no vacuum?
Vacuum:
it takes 4200 J/kg to increase the temp ...
- 103
0
votes
0
answers
17
views
Existence of liquid phase of metal below triple point pressure in vacuum chamber
As part of my work, I perform localized heating of metals using a CW laser, upto and past the melting point, inside a vacuum chamber with typical ambient pressures of $\sim 10^{-9}\,$mbar. However, I ...
- 83
0
votes
1
answer
28
views
Physical microscopic origin of vapor pressure and relation to bond strength
Currently, I am examining the vapor pressure of the elements as a function of temperature within the periodic table (as can be found from this resource from TU Wien https://www.iap.tuwien.ac.at/www/...
- 83
0
votes
0
answers
29
views
How Ultrasonic diffuser work?
i have studied A2 physics where i have learnt resonance and evaporation, i wondered how the ultrasonic diffuser work. my inital thought was that i guess water have it's own natural frequency, the ...
1
vote
2
answers
118
views
How do we cool exactly as sweat evaporates from our skins?
We all know that when our sweat evaporates to the air we feel colder, but since this process is a latent heat transfer our body temperature will not change, then if our body temperature is constant ...
1
vote
1
answer
64
views
Finding the equilibrium vapor pressure of two solutions(of different concentrations) enclosed in a vessel
The saturated vapour pressure above
an aqueous solution of sugar is known to be
lower than that above pure water, where
it is equal to $p_{sat}$, by $\Delta p = 0.05p_{sat}c$.
where c is the molar ...
1
vote
1
answer
333
views
Does the amount of water vapor air can "hold" depend on the temperature of the 'water' or the temperature of the 'air'?
The amount of water vapor that the air in a large region (say a suburb) can hold should be dependent on the average temperature of the liquid water within that region. Not the air temperature of that ...
- 1,165
3
votes
3
answers
333
views
Why don't clouds gradually evaporate and never come down as rain?
Clouds are present in the troposphere . So the radiation from the Sun first needs to pass this layer of the atmosphere to come down which means that the clouds above are constantly being radiated from ...
- 6,750
2
votes
1
answer
34
views
How exactly does air accommodate water vapor?
I would like to have clarity on how air accommodates water. When water vaporises, does the water molecules just squeeze into the space between already existing molecules of nitrogen and oxygen? From ...
- 913
4
votes
1
answer
376
views
What does 'saturated' air actually mean?
I'm having some problem in getting an insight on what 'saturation with vapor' actually means. The question is asked in the context of atmospheric air becoming saturated with water vapor and beginning ...
- 913