Two Hydrogen atoms covalently bonded to one Oxygen atom. One of the more common compounds on the surface of the earth.

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3answers
358 views

Can anyone estimate what proportion of water remains after I flush a toilet?

Imagine I have a clean toilet with some amount of water in the bowl. When I flush the toilet much of that water will be displaced by the tank's water. I want to work out (or model really) what amount ...
1
vote
2answers
868 views

Why droplets of water under oil explode when heated

In experiment, cold skillet with droplets of water was filled with layer of oil and heated. The droplets started exploding. Why water can not leave skillet less violently, like steady chain of steam ...
0
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1answer
2k views

Anomalous Expansion Of Water

How can the Anomalous Expansion of Water from 4$^\circ$C to 0$^\circ$C be explained with reference to subatomic particles?
1
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1answer
446 views

Does the Relative density of water change based on the state it is in

Will Relative density of water change based on the state it is in? Ie solid, liquid, gas. What causes this change(if any) in Rd?
8
votes
2answers
6k views

Why does water pouring from a glass sometimes travel down the side of the glass?

If you have a glass of water, say, three quarters full and you pour it at an angle of say, $45^{\circ}$ with respect to the the table, the water comes out of the glass and goes directly down towards ...
2
votes
4answers
1k views

What happens to water level when ice XII melts?

There exists this famous idea that if all floating icebergs melt, water level will stay the same (because the water replaced by ice is the volume of the melted ice). Now, Is this always so, if you ...
1
vote
3answers
30k views

Relation between water flow and pressure

Is there any equation that states the relation between pressure and water flow. I.e. Let's say that in 1 hour with 8mca (water collum meters) pressure I obtain 50m3. What if (giving the same ...
22
votes
2answers
5k views

Why is boiling water loud, then quiet?

Water in my electric kettle makes the most noise sixty to ninety seconds before the water comes to a full boil. I have been fooled many times by the noisy kettle, only to discover that the water was ...
3
votes
1answer
285 views

Boiling when I plunge my french press?

Occasionally when I make coffee in my french press I experience something odd. It happens pretty infrequently but certainly enough to be curious about. I have the grounds ready in the carafe. The ...
30
votes
2answers
5k views

Before a once-warm lake starts to freeze, must its temperature be 4°C throughout at some point?

This is a problem I just started puzzling over, and I felt this would be a good forum to check my reasoning. So here are the relevant observations followed by my question: Water achieves its maximum ...
2
votes
1answer
266 views

How much water is destroyed in photosynthesis, relative to the world's supply?

Water is involved in the photosynthesis. How much water are we talking about compared with the total amount on water on Earth? Is it enough to have an effect on the average age of water molecules?
0
votes
1answer
5k views

Water Electrolysis Calculations

From Wikipedia (http://en.wikipedia.org/wiki/Water_electrolysis#Efficiency): The electrolysis of water requires a minimum of 237.13 kJ of electrical energy input to dissociate each mole. Each ...
4
votes
2answers
2k views

How does the process of freezing water remove salt?

How does freezing water to make ice remove whatever salts were in the water to begin with?
1
vote
1answer
289 views

Calculating temperature of water in the freezer

Assuming water volume ($V$), initial water temperature ($T_0$) and environment temperature ($T_e$) are known, what is the easiest way to calculate temperature of water in given time ($T$)? For the ...
3
votes
1answer
832 views

Static flow of water in the presence of a loudspeaker

The title, I don't know whether it's correct or not, but I came across a video in youtube, http://www.youtube.com/watch?v=_PkgQQqpH2M. The author of video used the title and hence I used the same. ...
6
votes
3answers
4k views

Why does a bullet bounce off water?

It is known that bullets can ricochet off a body of water. Is surface tension responsible for this or is this the same behavior we see when an asteroid ricochets off the atmosphere? I don't think ...
5
votes
2answers
171 views

Wave with mass transport?

I don't think this question has been asked on this forum before (at least I didn't find it). In the case of a tsunami, an earthquake generates a wave which will travel with the sea/ocean as the ...
3
votes
2answers
184 views

why water molecules in vapor contributes to the green house effect and water condensed in drops not?

I am a teacher planning a unit on climate change. I came across this statement: "Clouds are water vapor (green house gas) and water molecules will reflect heat into space… actually clouds are ...
1
vote
1answer
370 views

How to model water flow with and without friction against other objects?

I am interested in modeling water flow including boundary flow (with friction) against other objects in the path of the water flow. I'm not a physicist but I am interested to learn the relevant ...
6
votes
1answer
306 views

Water flushed down, water pumped up (in buildings)

I live in a tall building (20 floors) on a mountain. Because the water pressure from the water company is not enough, there is a water pump at the last floor which is activated each time someone is ...
3
votes
1answer
129 views

Experiment to find structure of water

Who first determined the structure of water (two hydrogen atoms stuck to an oxygen atom at approx 105 degrees), and, more importantly, how was this done?
6
votes
1answer
618 views

Microwave oven + water: dielectric heating or ion drag?

When you place a water or food in a microwave oven, it heats. Which process commits more energy to that: dielectric heating, or ion drag i.e. resistive heating? AFAIK, in distilled water (which is a ...
1
vote
1answer
52 views

How do I determine when this object is about to get covered in dew? I can measure the environment parameters

There is a large disk of glass sitting outside, it is pretty thick and wide. Via different sensors hooked up to a controller, I can measure the air temperature, glass temperature (on the surface), and ...
1
vote
1answer
2k views

How much disolved oxygen is removed by boiling water?

Apologies if this is a chemistry question I've read that drinking water contains dissolved oxygen to the tune of $10\:\rm{ppm}$. I've also read that raising the temperature of water will remove some ...
7
votes
4answers
2k views

Sauna thermodynamics

Why does it get hotter (feel hotter) in a sauna when one pours water over the hot stones? Wikipedia says that the water condenses onto the skin, but the actual air humidity is so low that I doubt ...
3
votes
4answers
3k views

Why the shape of rainbow is semicircular after rain why not the whole atmosphere is colorful?

I have a very simple question. Everyone must have seen the rainbow after rain. According to the theory the rainbow is created due to the passing of sunlight from small drops of water in the ...
2
votes
2answers
3k views

Microwaves vs Gas or Electric Coil heating of a water boiler in a typical household

Wouldn't it be more energy efficient and or safe to use microwaves to heat our home's water boiler instead of using dangerous gas or hot electric coils that could catch other things on fire? I'm kinda ...
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vote
1answer
3k views

Can I calculate the maximum concentration of sucrose that will dissolve in water at STP using physical constants?

I am interested in identifying the maximum solubility of sucrose in water. Can this value be estimated based on the physical properties of sucrose? Eventually I will need this in degrees Brix (%w/w). ...
5
votes
5answers
6k views

Why does hot oil explode when pouring water on it?

I am puzzled to know, What is the reason of hot oil make sound and explode when we pouring water on it?
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1answer
5k views

Is sea water more conductive than pure water because “electrical current is transported by the ions in solution”?

Apparently, electrical charge is transported by the ions dissolved in water, is this true?
-1
votes
1answer
222 views

I want to recreate a phenomenon I've noticed from our water tank [closed]

I'm trying to recreate a phenomenon I have noticed from our water tank at home. Ok so we have a deep well pump that fills our water tank everyday. But something odd always happen everytime the water ...
2
votes
1answer
341 views

Calculating spacecraft water leak flow rate

A large container of heated water is floating in space. How can I calculate leak rate if a small puncture is opened? I'm assuming the water is kept at 298K and in the liquid state inside the chamber. ...
0
votes
1answer
88 views

The force of a phase transition

At standard temperature and pressure, I fill a bottle to capacity with $N$ liters of water, then place a weight of mass $M$ kg on its opening to serve as a lid. What values of $N$ and $T$, where $T$ ...
2
votes
4answers
3k views

Which is more efficient, heating water in microwave or electric stove?

So our propane tank in the kitchen ran out again today. Which is more energy efficient, boiling water in a microwave on an electric stove? All things being equal i.e. starting temperature and mass ...
2
votes
2answers
1k views

How the pipes of water don't freeze in -40 celsius?

Does anyone have a good answer how comes that the water in the pipes in our houses doesn't freeze even if it is -40 celsius for a whole week? of course assuming we don't make the water to fluid in it
11
votes
4answers
2k views

Thermodynamics of supercooled water

Now that it's been freezing outside for the last few days, I experimented a bit with supercooling. I've left a bottle of clean water outside for a few hours, and behold, when I shook the bottle, the ...
4
votes
2answers
2k views

Why are refrigerators 4 degrees and freezers -18 degrees?

I assume that the refrigerator's temperature of 4 degrees has something to do with the fact that water is densest at that temperature. Does that inhibit microbe growth? But what about the freezer, ...
4
votes
1answer
1k views

Cooking pasta: why does adding a lid lead to overflow?

When cooking pasta, some organic foam usually forms on the surface of the boiling water and the situation can be kept under control by adjusting the heat (and/or adding some oil). Covering the pot ...
0
votes
1answer
605 views

Temperature change effected by electric heater [closed]

A 40-gallon electric water heater has a 10kW heating element. What will the water temperature be after 15 min of heating if the start temp is 50F degrees. There must be an equation. I can't find it ...
2
votes
1answer
112 views

Clouds in closed hydrosphere

Is possible estimate the needed size of an geodesic dome (like in the Eden project) for creating an real hydrosphere - especially clouds (and rain)? With other words, under what circumstances can ...
1
vote
2answers
1k views

How thin a filter to filter particles out of salt water to make salt for human consumption?

I have gathered some salt in the Death Valley and for the fun of it I would like to clean it and make it edible. The process I plan to follow is simple: Dissolve the salt in water. Boil water for ...
7
votes
1answer
147 views

Polar ice deposits on the Moon - dispersed in permafrost loose rubble, or also massive/layered?

Water has been discovered on the Moon with remote sensing methods. Read the press release Diviner results indicate presence of widespread ice on the Moon on the "Diviner" infrared instrument on the ...
2
votes
0answers
1k views

Easy to obtain liquid with freezing point a couple of degrees above 0 Celsius [closed]

Please advice me a liquid whose freezing point is 2-5 Celsius. I know that the solution of salt in water can have freezing point of about -3 Celsius. I would like to know if similar liquid but with ...
0
votes
0answers
2k views

How to determine size of a Heat Exchanger?

I am designing a Tube heat-exchanger, similar to this: My process requires water (at room temperature, 18C ~ 22C) that is being pumped out of a small tank (300 Liters) to be heated in a ...
7
votes
1answer
83 views

How plausible is a subsurface ocean on Pluto?

According to this article on physorg.com, it's likely that Pluto has a subsurface ocean of liquid water. It suggests that the ocean would be about 165 km deep, under an equally deep crust of solid ...
3
votes
3answers
2k views

Does stirring water in a bucket in whirlpool keeps it warm?

I did an experiment when I was a teenager. I want to prove/see what really went on in that experiment. When taking a bath, take a warm water in bucket and start taking a bath. You will notice that ...
3
votes
1answer
1k views

Where are the ice rings in X-ray crystallography located?

I threw this image of one of my protein crystal's diffraction pattern (not the greatest) on a poster, and was wondering where (what reciprocal dimension) the ice rings are located as it might be a ...
13
votes
2answers
1k views

Why doesn't water come out of tap/faucet at high pressure when I turn it on?

(tap=faucet) When I turn a tap on full and then put my thumb over the spout covering, say, 90% of it, then the water spurts out. If I turn it on to, say 10%, then the water dribbles out. What's the ...
4
votes
2answers
2k views

Is a given volume of sparkling water lighter or heavier than the same volume of still water?

I can see it two ways - if all the $CO_2$ has turned into bubbles I would imagine it is lighter. However dissolved $CO_2$ atoms are probably heaver than the $H_2O$ atoms they replace, or fit in ...
6
votes
1answer
597 views

Why does blowing on someone who is wet feel colder than on someone who is dry?

The title says it all. If I'm standing in the wind and I'm wet, I feel much colder than when I'm dry. This is true no matter how warm or cold the water. Why is this?