Evaporation Definition and 215 Threads

Some facts: Water does evaporate. The average kinetic energy of a water molecule at 373 K is ~0.03 eV The average strength of the H bond is ~0.24 eV In the liquid phase the average H2O molecule is bound by 2 to 4 H bonds...

I have a question regarding the evaporation rates of water in different colored materials. Kirchoffs laws of radiation state that a black body is both a perfect absorber and emitter of heat. This also means that a black material will cool down quicker than a white one. So if I had three buckets...

Hi all, I was just wondering how I could recreate this at home What parts do I need? Thanks, Harry

This picture confuses me. It showed here that the red particle at top right get suck into the black hole. But to a distant observer, everything near the black hole get time dilation and finally freeze at the horizon, right? So, "when" the black hole evaporates? Moreover, why the black hole likes...

Is there a formula relating "temperature feel" to measured temperature and evaporation of water in an evaporation pan (in mm)? I have data on: *average temperature *evaporation of water in an evaporation pan *minimum temperature of water in an evaporation pan *maximum temperature of water in an...

Hi I was thinking of doing an experiment for my maths coursework to plot a graph to, and was thinking of doing something related to the rate of evaporation of water. My thinking is that i conduct an experiment where I heat water to boiling point so it is at about a constant temperature with a...

Hello there, During an experiment I had for my MSc Thesis for ammonia extraction, I used WWTP sludge and biogas digestate with an evaporation/distillation unit. I tried different combinations of sample vol. and evaporating flask vol. and then I added vacuum pressure. At first pH was dropping...

As we all know that in atmospheric pressure (1 Bar) saturation temperature of water is 100 deg C. And the air contains mixture of dry air and water vapour. My doubt is here that the water needs 100 deg Celsius to change from liquid to vapour state then how can a normal room temperature air...

1. Water evaporates under atmospheric pressure. Without changing the temperature , the same water is placed under partial vacuum . The rate of evaporation will a] increase b] decrease c] drop to zero d] remain unaffected 2. No eqns reqd3. The evaporation is a slow process that can occur at...

Hello! I've been researching hygroscopic materials and evaporation rate a bit lately, and a question has struck me which I haven't found an answer to yet: What material factors affect the rate of evaporation? Is it possible to engineer a material which is hygroscopic (absorbs water) in humid...

Hi all, When talking to some of our optics vendors, I got the impression that Ion Assisted Deposition (IAD) is standard. We use our optics at high power densities and we care about laser damage as well as adhesion and density of the coating (aka porosity, helps reduces sensitivity to humidity)...

Hello everybody, I have the following problem: I have a fuel tank, with a liquid phase (the fuel) and gas phase at To and P0, where T is temperature and P pressure. I assume that the gas phase at the instant t=t0 is air. (Is this assumption correct?) The temperature of the liquid phase...

I hope it is ok to post a rather pedestrian question to those of you who may laugh. We own a vacation home in Phoenix and continually folks insist we should leave pails of water in the house while we're away to help raise the RH and keep construction materials from drying out, cracking etc. This...

Homework Statement Hi, I am came across the following question and can't quite make complete sense of it: "Explain, in terms of internal energy, why a liquid cools when it evaporates". Homework EquationsThe Attempt at a Solution Could someone tell me whether this questions is implying random...

I am trying to give some context to medical vaporizers in a literature review I am composing and initially decided to give asthma inhalers and nasal inhalers as examples. I realized however, that some sources on-line were referring to these metered dose inhalers as vaporization devices when...

Homework Statement Ina light bulb, billions of electrons flow through the tungsten wire bumping around, causing the filament to glow hot. Hot tungsten evaporates slowly, so its initial thickness profile r(x, t=0) can change over time. Consider a volume V of tungsten, with N bonds total, each...

This is extemely important to me! In an isolated system of a very large box half filled with water, a small soaked sponge is placed just above the surface of the water. Will the sponge eventually dry? At first I thought not. But the molecules in the vapour above the water might have a higher...

Homework Statement Ethanol evaporates in a 10 x 20 x 50 ft3 room. Air is initially dry at a temperature of 30 °C and 765 mmHg of pressure. a) If the partial pressure of ethanol after vaporization is 40 mmHg, how many pounds of ethanol evaporated? b) The same air is compressed until it reaches a...

If I throw 10 gallons/minute of cold water for 4 days into an oven that's 300°C Celcius and 300ft long sloped at an angle of 10°, how far would the water make it down the oven before completely evaporating? Even if you can't solve this directly, I'd love some advice or recommendations of how...

I just began reading Feynman lectures and it turns out that during evaporation, water molecules that move faster than average (higher temp) break away from the attraction of their neighbors leaving behind molecules that move slower than average (lower temp) and result in a cooler liquid. When a...

Hey, I have a question for evaporation--What is the real driving reason for evaporation? I usually believe that it is a pure diffusion process: the saturated pressure of liquid at the liquid vapor interface is higher than the partial pressure of vapor in the ambient, and this pressure difference...

I'm puzzled by a phenomenon that my daughter pointed out to me. If you have no plastic ware in the dishwasher, your glass and ceramic dishes will dry faster. Slow evaporation from plastic is easy to understand; the water beads up and presents a smaller surface area. What I'm not clear on is why...

What is nuclear evaporation (e.g. proton or neutron evaporation)? Someone can explain? Thank you very much, Matt

Hello all, I use an evaporation chamber at my lab every day. Basically, put some substance in the chamber, close it, bring it down to vacuum, and pump enough current through it to vaporize it where it deposits on a substrate. I've been using 175A to create a deposition rate of about 1...

Hi there! My first post, exciting. What I'm after is a little help steering me in the right direction. I'm attempting to model evaporation in a closed system, and I'm not sure how to go about it. That is, let's assume we have a liquid in a partially filled container, and the rest is filled...

So this is the problem that I am working on. It is a woosh bottle where I am inputting 70% isopropyl alcohol, closing the top and waiting for the alcohol to evaporate. This mixture is then ignited to generate a flame. My job for this project is to calculate the maximum volume of 70% isopropyl...

Homework Statement Water's heat of vaporization is 2260 kJ/kg. How much power would you need to apply to water so that the evaporation rate was .25 g/s? Homework Equations Not sure The Attempt at a Solution What equation can be used to find the given rate?

hello, i am crowed and i need help, first of all i am thankful for every help, terms are : i have 2 clay pot 1 small and 1 big one, on picture black sticks are pot, the small one is inside the big one and empty space is filled with sand, i am making this sand wet and after some minutes next...

It is known that boiling point of water is 100C or evaporated at 100C and atmospheric pressure. why we see that water evaporates slowly at all temperature.

Is it possible to make a liquid evaporate solely with vacuum? If you were to reduce the pressure in a container of liquid to 0, while also insulating it from any outside heat, would it remain a liquid or turn into a gas? If it turns into a gas via lack of pressure alone, does the...

Hello I have a few fundamental questions about evaporation 1. In Cengel's Heat and Mass Transfer, in all sample and practice problems the author assumed without explanation that for a system such as a pool of water exposed to air, the air immediately above the liquid surface is saturated (100%...

Preface- I am anoob scum who doesn't know much How and why does an air conditioner gas cool when it evaporates. Exactly how does the gas's molecular kinetic energy lessen, and more specifically how does the kinetic engery from the room and pipe that holds the gas, get transferred to the...

Hello, i am working about pot in pot refrigerator (zeer) and i have problem with calculation, i have to calculate how many % energy will be lost during T time, i know theory about this effect but i don't know how to calculate it, i have some reference but my english and math skills aren't...

i have question.. i need some to help me to solve it.. the Fact said that " when we reduce the pressure exerted on free water surface, the evaporation rate decrease"so i am searching for formula that related between the evaporation rate and pressure and volume

Homework Statement For which process does the system absorb energy in the form of work? a) Water Evaporates into steam. b)Air is compressed by a bicycle pump. c) Both Homework Equations The Attempt at a Solution I though the answer was both. However, the key says the correct...

Ok so let's say Earths atmosphere is 300 Bar. Would water at 100 degrees F and at 300 Bar still have evaporation or would it just stay liquid?

"Which statement applies to boiling but not to evaporation?" Homework Statement Which statement applies to the boiling but not to the evaporation of a liquid? A The separation of the molecules increases greatly B At normal atmospheric pressure, the process occurs at one temperature only. C...

Hello, This is basic stuff and I feel a bit embarrassed for asking this, but here goes: From what I think I know, evaporation is always happening in a liquid (water, for example) irrespective of the vapor pressure, but boiling only occurs when the vapor pressure is equal or greater than the...

Hi, what is the differencce between flash evaporation and cavitation ? Can i apply cavitation model for flash evaporation in cfd ? Thanks

I'm missing out on something here. I'm studying how the cooling tower works and it says that the "water evaporates and removes heat". The thing is, shouldn't the heat be added to the water for it to evaporate and thus increasing the heat? If we want water to evaporate, we boil it with fire...

Black holes have an entropy, but they evaporate. At the end of the evaporation, the entropy is greater than the entropy at the beginning of the evaporation. I am looking for an example of a quantitative result for the entropy of the black hole after evaporation (or the entropy difference...

Arkani-Hamed, Dubovsky, Nicolis, Trincherini, and Villadoro argue in section 2.2 of A Measure of de Sitter Entropy and Eternal Inflation that the effective field theory description of black hole evaporation fails after a time tev, even though the curvatures are small. Almheiri, Marolf...

I have recently wondered how water can dry at normal, livable temperatures, but its boiling point is 373.15K. Is there a difference between drying water and boiling it into a gas?

I wonder if there is any law for heat exchange. I have learned that heat exchange between systems occurs when the temperature of respective systems differ. But in case of evaporation, the process creates a cooling effect even in an isothermal condition ( I mean by isothermal condition to be a...

I understand the differences between evaporation and boiling as stated in secondary school textbooks. But I would like to know, can evaporation occur at or above the boiling point? I think that, since evaporation is the escaping of high energy molecules, then when the water is boiling, there...

Homework Statement The air is at 50% humidity and the temperature of the surface of the ocean and the air is 20degrees C. What are the two critical processes that must occur to ensure there is continued evaporation in the absence of external energy sources? Homework Equations Relative...

I hear that black holes evaporate, but does it all get converted into Hawkins radiation? And what role do white holes play in evaporation?

1.Is sensible heat involved in the equivalent evaporation of boiler? While studying about the equivalent evaporation of boiler I got confused about the equation. The equation says,2. E=Total heat required to evaporate feed water/2257(latent heat of water) The definition of E is the amount of...

I know that incandescent bulbs are filled with some inert gas to reduce the rate at which the filament decays. If the filament was to be exposed to ambient air, how long before it evaporated? How long can a mesh of light bulb filaments (or other material with as high a melting point that can be...

What is the maximum approximate black hole size that would have negative growth rate as a function of average local mass density (and/or any other relevant parameters)? In other words, when does an evaporating black hole become a growing black hole and vice-versa? Cheers Eric