Evaporation Definition and 215 Threads

Looking at the steam table below, if I understand things correctly, it will take 419kJ to bring a kg of water to the boil at 100°C and a further 2257kJ to turn all of that boiling water into steam. I assume that would have to be in an open boiler, as the pressure inside of a closed vessel would...

I have had an idea kicking around in my head for some time now. It all started last summer when I was kayaking down a river and I had stopped in an eddy to relax for a moment. The rate of flow of the water was strong enough to make sizable vortices along the eddy fence around the boulder that...

I need to make a gas consisting of 1 % h202. Would pouring a liquid consisting of 1% h202 and 99% h20 into a pitre dish ,and using a small fan directed at the surface result in a gaseous solution of 1% h202. The answer seems simple to me, but I have no background ,and am usually wrong in...

Since heat is transferred from a region of high temperature to low temperature if a few molecules have more energy, it would be transferred to the surrounding molecules. So if a molecule has 10J of heat it can only transfer some energy such that they have the same temperatures as each other...

Why water condense when high pressure was applied and reduce to lower pressure?(I observe this when I play with water rocket, when I pump air inside there are no vapor, but after I shoot it, there is vapor coming out.) Does water condense at 100%< humidity? Does water vapor condense easier...

Can a substance only evaporate at the T(sat) at that particular pressure and why not even at a higher temperature? Example of a refrigerant at room temperature, pressurized container. But when it's opened, the P falls and T(sat) falls, so it goes to that T(sat) temperature to evaporate. But...

Why is it that neutrons evaporate from nuclei more easily than protons do? Intuitively, since protons are electrostatically repelled (in addition to whatever nuclear forces they have in common with neutrons), one would expect protons to be ejected more readily than neutrons. (Maybe this is...

Homework Statement A dish has a shape described by the equation: h=(x^2+y^2)^3/2 At time = 0 it is filled to a height of 20cm with a fluid that evaporates when exposed to air. The evaporation rate is proportional to the exposed surface area (that is decreasing) at any time t. if h(t) is the...

Homework Statement Homework Equations Given in problemThe Attempt at a Solution Hey guys So I have this problem I'm working on and I just can't seem to get too far with it. I've gotten half of the first part...I'm just having trouble integrating the equation I got...and I don't even know if...

So my friend came home from work and asked me why adding vinegar to water aids in evaporatoin. He said they had them clean with this solution because it helped the water dry up faster. However, I've only had two years of study in chemistry and I can't say I know for certain. I know that...

Hi, I would like to know if somebody has the formulas to find the heat transfer coefficient while the nucleate boiling and the film boiling, for a plate heat exchanger... I really look forward reading someone. Thanks

I am trying to determine whether the evaporation rate of a 3L erlenmeyer flask would be negligible given the following circumstances. The flask would have a rubber stopper in it, with a hole approximately 1mm in radius greater than the steel drip line feeding into it (leaving an open ring that...

hello guys if the water surface is at same temp as air above, and humidity is 100%, do any wataer molecules leave their liquid state to become vapour ie evaporate? I couldn't remember what professor said exactly, so i checked up on internet and it says water can't evaporate at 100%...

Long story short I'm making some nanoparticles and one of the steps require me to evaporate THF(tetrahydrofluran) out of an aqueous solution containing the NP's. This needs to be done under a partial vacuum with only one intake valve(I know, it sucks but I have no other option). I'm looking more...

Hi, it has been a while since I've been on PF. I know that the rate of evaporation depends on the relative humidity, temperature, pressure and surface area. Is there any formula that fits this criteria?

I'm looking for a general model that I can use to approximate the evaporation rate of a small pool of liquid. The purpose is to calculate the rate at which a few mL of liquid is evaporating at the bottom of a cylindrical test chamber for an experiment. I figured that I wouldn't have any trouble...

Assuming that black holes do in fact evaporate via Hawking Radiation, how can an infalling observer ever get inside the event horizon if the black hole evaporates in a finite time from an outside observers frame?

Hi I had a question regarding an example about mass transfer. I already have the solutions to this but there is one thing I am confused about. The problem just asks the rate of evaporation from the water-air surface to the atmosphere at a given temperature, pressure, and relative...

Homework Statement If the air is at100% relative humidity and a water surface is at the same temperature as that of the air above it, do any of the water molecules leave their liquid state to become vapour? Homework Equations r=\frac{e}{e_s} Clausius-Clapeyron equation: \frac{de_s}{dT}=...

How would i go about calculating the loss of Bourbon 120 proof 60% ALC/VOL and/or Water from a wooden barrel stored in a warehouse, knowing the ambient temp, RH% and Dew Point, Know as the angels share. per period of time?

I am doing a senior design project regarding water hydration and did some tests to get a general evaporation rate. I assumed that evaporation is proportional to the surface area of the water to air boundary so I thought that the water level of water in any constant cross section container should...

I am trying to create a solar refrigerator which is roughly based on the Zeer Pot idea...

Homework Statement A pond contains 1,000,000 gal of water and an unknown amount of chemical. Water containing .01 gram of this chemical per gallon flows into the pond at a rate of 300 gal/hour. The mixture flows out at the same rate, so the amount of water in the pond remains constant. Assume...

Hi I was just wondering how rates of evaporation changes with initial temperature. I was also confused because does say water have to be at 100° C before it starts evaporating or can it start earlier? Thanks

as a process worker may someone with more technical knowledge answer question below please 1. we have a juice which contains some Carbon.I am finding it harder to evaporate due to the Carbon.Why is juice harder to evaporate with Carbon in it then juice without Carbon? Cheers Trent H

During black hole thermal radiation can mass be radiated while entropy stays? Is it possible that entropy stays in the singularity?

Hello! I'm trying to build simulation of steam generation process My problem is this: I want to know how to calculate pressure in the following problem- closed container, V=1 litres 121 C water, 1 g 121 C saturated steam 1.129 g p = 1 bar if container valve opens shortly and...

Can a solid, no matter how small, even a single cell, be evaporated with water vapor from a pool of water?

Evaporation is a cooling process. What cools and what warms? Also, condensation is a war,ng process. What cools and what warms? I understand that during evaporation the water molecules of water slow down therefore cooling down. But does this mean that the air warms up? The opposite goes for...

Hi, On various websites I read that 70% of the heat loss of a pool is by evaporation, whereas up to 85% of the solar radiation can heat an uncovered pool. We use 22mm thick black color EPE panels to cover our pool. On a sunny day, is it better to cover the pool or to leave it uncovered ...

Hello everyone! I am trying to design a magnetic testing apparatus that needs to remain at -196K for 20 minutes. There is not exactly a straight foreword equation to get a calculation for the evaporation rate of liquid nitrogen. The apparatus looks like this, and I have highlighted the area...

Homework Statement In case of an isobaric evaporation, why the temperature must be constant? Homework Equations I'm working on Mollier Diagram and my textbook says "because P is constant, so T is also constant", I coundn't understand it anyway The Attempt at a Solution

Hello, I have 3 questions please 1. Why does Alcohol evaporate easier then Water? 2. Why do liquids with a Higher Solids content have a higher boiling point then liquids with a lower Solids contents.How and why does Solids affect evaporation? 3. Why do liquids when under a lower...

Homework Statement - if I put 0.3 litres/squaremeter of hot water (50 C) on ice rink (-5 C), how long will take to the water to be 0 grade C ? How much evaporation moisture will be in the air (5 C) and how long will be the time for evaporation ? Homework Equations Heat load=...

Homework Statement A steam driven turbine generates 200 MW of mechanical power at tan eficiency of 32%. The temperature of the steam at the input is 500 C, and at the output it is 200C a: How much power is input as heat to run this turbine? b: How much power is lost in hear to the...

I'm looking to do a little flash animation illustrating evaporation at a surface however I've been having a lot of trouble implementing this. My initial Lennard-Jones approach was a disaster. I then tried hard-spheres and this wasn't really any better. I've considered something like a hard...

Hi, When studying and thinking about the concept of Specific Latent Heat of Vaporization I keep falling in the trap of confusing it with evaporation - in the end, in both cases water in the liquid state is being changed into vapor. Could anyone help me differentiate the two ideas...

why is evaporation rate (e.g. of water molecules) faster in the presence of the electric field? I understand that the water molecules become polarized and hence feel electric force... can anyone explain more specifically? thnx! =D *b.t.w. if you're interested in figure skating, please...

Hi! I am Calculating the uncertainty in an Evaporation Rate i obtained from measurements around a lake using E=C.U(ess-ea)/P where C is constant 135mm/day at 1.5m above lake surface, U is average wind speed, P air pressure hPa, ess saturation vapour pressure @lake surface temp (Ave), ea is air...

Homework Statement A pool has chlorine-free water. The chlorinator is turned on, dissolving chlorine in the pool at a rate of 30g/hr. But the chlorine has an escape rate proportional to the amount dissolved in water. This pool's escape rate is 13g/hr per 100grams dissolved. a. Write a...

Homework Statement "You allow 1kg of saturated liquid water at 100 degrees C to evaporate in a room with a constant volume. The final pressure is 10kPa. The initial and final temperature are equal, and the walls of the room are maintained at 100C. Use steam tables unless otherwise indicated."...

I'm working on a project where I'm trying to find the differential equation of a falling raindrop. The drop I'm considering will be under 10mm to eliminate the drops breaking apart and I've found that for that size, the drops will be spherical and traveling 6-8m/s. I've determined my air...

I am interested in understanding and being able to calulate the rate of evaporation and the volume lose over time of the salt water. Surface area is 190 sf Depth 4' average air temp 75 deg. F Daylight hours 12 Average wind speed 5 mph Humidity 65%

Homework Statement In this problem, the surface tension S represents the work done to the water when increasing the water's surface area. The vaporization temperature Qvap represents the energy needed per volume unit to vaporize water at 100 degrees Celsius. We imagine that water molecules...

Hello there, Right now I'm in a physics lab in which I have a vacuum jar, a thin film evaporation apparatus, and the instructions to do something interesting. I'm looking at a bunch of ideas right now, but one project that appeals to me is a multi-layer anti-reflective coating. The way I'd...

HVAC man here, still tinkering with humidification. Trying to get a baseline on the rate of evaporation of undisturbed water in a full container in a room with a fixed RH & temperature and no air currents. It's a cool (unheated) very small, room in my basement with a door on it. The room has...

Everyone who lives in a region that gets cold knows that if you exhale onto a window, the water vapor in your breath condenses onto the surface. Because the air is dry, this condensation evaporates. What puzzles me about it is why it does so from the edge of the fogged region to the center, as...

Interesting question to think about. We know that there are lots of comet bodies in the Oort cloud and we know that even in the near absolute zero temperatures evaporation does take place. Comets are usually covered in dust, which slows down this evaporation, but let's consider clear body...

Homework Statement Two grams of water are sealed in a rigid con- tainer; then the water is vaporized by heating. 1664 cal of heat is needed for vaporization. What is the change in internal energy of the water? Answer in units of J. Homework Equations 1 kcal= 4,186 J The Attempt...

hi, Can anybody explain the phenomenon behind internal energy? and what is the change in internal energy when water evaporates. Please do give reference to first law of thermodynamics. Thanks in advance.