Water Definition and 179 Discussions

Water is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, even though it provides no calories or organic nutrients. Its chemical formula is H2O, meaning that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. Two hydrogen atoms are attached to one oxygen atom at an angle of 104.45°."Water" is the name of the liquid state of H2O at standard conditions for temperature and pressure. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor.
Water covers 71% of the Earth's surface, mostly in seas and oceans. Small portions of water occur as groundwater (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor, clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%). Water moves continually through the water cycle of evaporation, transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.
Water plays an important role in the world economy. Approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of the long-distance trade of commodities (such as oil, natural gas, and manufactured products) is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of substances both mineral and organic; as such it is widely used in industrial processes, and in cooking and washing. Water, ice and snow are also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, diving, ice skating and skiing.

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  1. Delta2

    B EM waves in vacuum analogy

    So, is water for water waves, what is the vacuum for EM waves travelling in vacuum. I know the analogy can't be exactly perfect because water molecules oscillate in the presence of water waves, but in vacuum nothing seems to oscillate? Or the vacuum oscillates in some way? And no I am not...
  2. nik282000

    Fractals/Dendrites and the Dissolving of Phenoxyethanol in Water

    I shot some high speed footage of phenoxyethanol dissolving into water and observed some fractal/dendrite like patters at the edge of thin droplets that float on the surface of the water. I suspect that the water under the droplet becomes saturated very quickly as the phenoxyethanol is not...
  3. P

    How much time does it take to warm up water?

    Water heater has the effect 2kW and is filled with 2kg water, with a heat capacity of 4,18Kj. The water needs to be warmed from 300K to 400K. How much time does it take for it to warm up? I've tried to solve this, but it seems that i need to know the heat capacity of the water heater, which i...
  4. person123

    I Water Waves Over Obstacles: Higher Frequencies Grow, Not Decay

    In general, it seems that higher frequencies of a wave dissipate more than lower frequencies. For sound waves, it explains why you can hear lower pitches from farther away. For a vibrating string or plate, the higher frequencies also dissipate first, with the fundamental fading last. For water...
  5. M

    Condenser calculations - uncertainty

    A water cooled plate condenser, condensing refrigerant. Heat exchanger (condenser with plates) characteristics: Description symbol value value (converted) number of plates np 28 number of channels nc 27 number of water channels nwc 14 number of flowing channels for refrigerant...
  6. Johnnyallen

    Water pressure affects air pressure

    In the movie The Abyss an oil rig crew works and lives at the bottom of the ocean in a deep sea structure. There is a compartment where there is an opening in the floor allowing the crew to lower a submersible craft without going through any kind of air locks etc. We all should know from high...
  7. N

    Pressure in a sealed vessel

    I have a sealed vessel, it is 200 ml, it contains 25 ml of water which is then saturated with CO2 (bubbled through at 0.3 l/min unitil pH drops, ~ 1 h) at rt. The vessel is then heated to 130 °C. I wish to calculate the final pressure of the system. Thus far I have calculated the volume of CO2...
  8. manareus

    Instrument name for water sampling and analysis

    Hello, thank you for your attention in my thread. I'm the head of Youth Science Club on one of the many High School in Indonesia, I got many members and I want to guide them for doing water sampling and analysis. In the history of my high school, no one is able to do water sampling and...
  9. Zachrz

    Safe Endothermic reactions for skin

    Hi, Its my first time here in PF, I was wondering what could be a fast endothermic reaction(with water) that does not burn the skin/ cause severe allergic reactions when/after touching or in contact with the reaction. (With high rate of cooling and hopefully no bubbles or gas forming). E.g to be...
  10. L

    Superionic and metallic states of water and the Anomaly of Water

    https://www.wired.com/story/a-bizarre-form-of-water-may-exist-all-over-the-universe/ Black ice I knew the Black Ice Theories since around 1990 https://www.nature.com/articles/s41586-019-1114-6 -- Demontis, P., LeSar, R. & Klein, M. L. New high-pressure phases of ice. Phys. Rev. Lett. 60...
  11. Elder1994

    Find the electric dipole moment for a water molecule

    The equation that we saw in class is for a continuous charge distribution, I think that for this exercise I need to treat the system as a discrete charge distribution but I'm not sure. Also, I don't know how I can calculate the intensity of the electric field needed to move this charge.
  12. F

    B Sailboats providing their own wind

    I happened to be watching this cartoon and this one scene seriously bothered me... This... just feels like it wouldn't be a workable solution. Am I wrong? I can't say I perfectly understand how fans or propellers work, but I would imagine that by pushing air or water in one direction, equal...
  13. WhiteWolf98

    Clausius-Clapeyron equation to estimate sublimation pressure of water

    Before this question, the questions were about the Clapeyron equation, and how to estimate ##\Delta s##. I'm completely put off by this question however, and don't know where to start. I've found that the triple point of water is at ##0.01°C##, and there is indeed data in the table for...
  14. I

    Underwater thrust formula?

    I'm trying to determine the force needed for one object to displace another object underwater. Specifically, Object A strikes Object B hard enough to jettison it from the seafloor up to sea level/land, let's say the Pacific coastline. I have a timeframe in mind, density & mass of the two...
  15. somasimple

    Hydration shell software?

    Hi, Is there Hydration/solvation shell software? I mean softwares able to show ions/molecules and surrounding water molecules forming hydrations shell? https://en.wikipedia.org/wiki/Solvation_shell
  16. gazaah

    Vacuum suspended fishtank: Why would this design work or not?

  17. person123

    MATLAB API For Wave Flume Data Analysis

    (As a quick note, 'wave flume' should be taken rather generally. I basically just mean the sort of experiments involved in the flow of water which may use instruments such as pressure gauges, load cells, wave gauges, and ADVs. I know that they're not always done in a flume per say -- the...
  18. J

    A Negative pressure

    Hi everyone! I am working with the theoretical solid phase diagram of water and I would like to know what negative pressure means. Thank you in advance!
  19. C

    Comparing Water and Ice Melting for fighting fires

    Good morning, I'm wondering on this question for a while. Imagine we have a fire progressing in a corridor 30 meters wide at a known velocity. What kind of barrier (of the following) can be most successful in minimizing or even erasing this fire and why: a water-soaked area, or a zone covered...
  20. D

    Misc. Hydrostatics problem in a water vessel

    I am trying to design a water vessel system that maintains it's water level as it is consumed. In item 1. It's a simple water barometer, where the height of water in the column can be supported by atmospheric pressure until 10.34. In item 2. There are two columns that are open to atmosphere...
  21. doglover9754

    Why does water not follow the law of motion?

    So I was in the bus going to school. I sat in the back not directly underneath the emergency exit but more like behind it. Anyways, since it’s been raining consistently, the emergency exits sometimes leak. So I’m sitting down and my jacket sleeve gets wet with a drop from the emergency exit. I...
  22. C

    Flow of Water into a Bowl with Holes

    I'm facing a problem with that rhyming title up there. The design is thus: a downward-facing, vertical pipe with known constant flow and diameter has water flowing out of it, into a short (15cm-91cm) free fall. At the end of that fall is a bowl of indeterminate depth made of steel with holes...
  23. jappy190

    Calculating charge density of particular ligands

    Hi everyone, this is my first thread! I am currently undergoing a personal investigation that is based on one of the factors which effect the splitting of d orbitals in central metal ion by the charge density of ligands (in a complex ion). However, recently I got stumped by trying to...
  24. R

    Oil-Water-Salt - What's the force at work here?

    Hi, This is something I observed in the kitchen when I was cooking something. I had put some water in a vessel, to which, I added couple of spoons of oil. The oil formed large droplets on water surface. I then sprinkled normal table salt crystals on to the water surface and they sank to the...
  25. D

    Determining the flow rate for a cooling system

    MODERATOR'S NOTE: HOMEWORK INCORRECTLY POSTED TO CLASSICAL FORUM, SO NO TEMPLATE I need help with the following question: Please have a look at the question and my attempt at the solution. Alternative cooling systems are considered for a large computing centre requiring 1 MW of cooling...
  26. I

    Ideal fluid hitting a wall

    Hi, I`m seeking for help in the following problem. A flat vertical board is travelling in water which is to be considered as ideal. One of its ends is in water, the other one is outside the water. Its velocity is v with respect to its normal. What is the velocity of the water stream directed...
  27. L

    Calculating the wavelength of a surface wave after impact

    Homework Statement There's a bucket, filled about halfway with water. The water itself is completely still. A perfect sphere with mass m and volume v are given. The depth of the water, and the radius of the bucket (which may be considered perfectly cylindrical) are both given. In short, you...
  28. M

    Can we extract energy out of a capacitor in the ocean?

    Hello, sorry about my english it's not my mother tongue. I hope this is the right section to place this. 1. Homework Statement A cylindrical capacitor is placed in the sea so that when a wave comes (the water goes up), the water becomes the capacitors dielectric, when the wave has passed (the...
  29. A

    Clear formula for water penetration by wave frequency

    I want a clear formula for clear water (and salty water) penetration by giving only the radio wave frequency . I searched the web , the formulas on the web are so complicated . Are there any simple formula available for that ?
  30. G

    I Rippled surface on lake ends abruptly

    Hi. I've made these pictures on Reichenau Island in Lake Constance, Germany. I was suprized about that clear line between the calm area close to the shore and the more rippled surface further out. The wind was weak, but directed from water to land. From a pier I could see that the ground drops...
  31. S

    Best anode materials for water-based hydrogen generator?

    I want also to build electrolysis based hydrogen generator or and water oxygenator/aerator. It's simple electrolysis device but requires special electrodes that are corrosion resistant or at least safe for human consumption. I seen that hydrogen bottles use platinum titanium electrodes. Platinum...
  32. Z

    Carbon dioxide in liquid and gaseous phases with liquid water

    What are the differences between carbon dioxide solubility (miscibility, reaction) in liquid water when in gaseous (<38 bar) and liquid (>38 bar) phase? The temperature in my experiments is usually between 0 and 5°C. The stirring speed is around 500 rpm. Is the solubility given apart from...
  33. D

    What is water impact velocity formula?

    Hello Everyone, I am brand new to this forum and I am currently doing "student research project task" where I need to conduct my own experiment basically. I am currently struggling to find a formula for an impact velocity. I hope there is someone in this forums that could help me. What I...
  34. J

    Water sometimes drips from the exhaust of a running car...

    Homework Statement You may have noticed that water sometimes drips from the exhaust of a car as it is running. Is this evidence that there is at least a small amount of water originally present in the gasoline? Homework Equations not sure if there is one. The Attempt at a Solution I'm not...
  35. Boltzman Oscillation

    How does a the vertical force of gravity end in horizontal motion?

    When a stream of water falls perfectly vertical, some water hitting the surface will disperse horizontally. What is the force that causes this? References would be awesome!
  36. Delta2

    B Water colour in Mars

    I guess water in earth , in big lakes or seas, looks blue because the earth's sky is blue and the water's surface reflects the sky. Now if there would be some big lake of water at Mars, how the water surface colour would be? I guess the colour of Mar's sky which is red (right or wrong?) It is...
  37. B

    How do I find an enthalpy value if my temp. is below 50 deg. celcius?

    I wanna design a curding machine (Milk to Cheese) with an open system that operate at isobaric process (contant pressure), P = 1 atm = 1,... bar the range of temperature is = 25-75 0C can i find an enthalpy of water from Mollier Diagram if my temp. is 25 to 75 degree celcius ? how ? from my...
  38. Gabriele99

    Will water flow ever stop if we increase resistance?

    Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels...
  39. G

    Air pressure holds coaster on glass: What if only half full?

    Hi. If I fill a glass with water up to the top and close it with a coaster, I can turn it upside down without the coaster falling off and spilling everything. Usually, this is explained with the atmospheric air pressure being bigger than the pressure of the water inside the glass (hence, it...
  40. M

    Can you separate hydrogen and oxygen molecules?

    Is separating hydrogen and oxygen molecules possible? If so, how?
  41. SemM

    Why is octanol prioritized for partition coefficients?

    Hi, it is well established that octanol is the preferred solvent for partition coefficient studies in environmental chemistry, however, some studies ui.e Noble A. Parition coefficients (n-octanol-water) for pesticides) J Chromat. 642 3-14, mention that estimating toxicity based on solubility in...
  42. Dami121

    Height of a Heron's fountain

    Homework Statement I have this homework on how a Heron's fountain works. The exact assigment is as follows: "Construct a Heron's fountain and explain what (which variables) influences the height of the fountain." I've already constructed it and it works well, but I'm not so sure about the...
  43. H

    A Do Falaco solitons also occur in water on a microscopic scale

    Falaco solitons are unique in their longevity, reportedly up to 15 minutes on the surface of a body of still water. For details and the math see {{ http://www22.pair.com/csdc/pdf/pdf/falsol.pdf }} In addition, this persistence occurs at relatively macroscopic sizes in the range of 10 to 40 cm...
  44. alphaj

    Chemistry ORGO: What does it mean when a molecule is 'quenched?'

    Homework Statement n/a Homework Equations n/a The Attempt at a Solution n/a Just a question. I keep seeing that in SN2 reactions, sometimes a molecule is quenched by H2O or H3O. I've seen it turn an O- into an OH and also a heteroatom into an H. What exactly is going on here?
  45. UMath1

    Divergence of downhill flowing water

    I just learned that an incompressible fluid must have zero divergence within a given control volume. Given that the divergence of a fluid at a point(x,y,z) can be found by taking the scalar sum of the of the x, y, z acceleration vectors at the given point, wouldn't this mean that water flowing...
  46. ISamson

    Is water really necessary for life?

    You know how they always say that without water there would not be life, right? Astronomers also look for life on planets with hints of water in their spectrum. But is water really necessary for life? Some ET life could not be a tiny bit similar to ours and might not even need water or water...
  47. D

    Does capillary action use water heat energy?

    Capillary action is a form of work, i.e. an object (water) moved by a force (capillary action) over a distance. Since all work requires energy, what supplies the energy for capillary action? Is the chemical energy of the water increased by adhering to a surface? Perhaps the heat energy of the...
  48. A

    Why does bathwater in a plughole spin AT ALL

    I don't care whether it goes clockwise or anticlockwise so this is not the usual Coriolis conversation. Why doesn't it just go down straight?
  49. V

    Help to determine convection coeficent or temperatures

    Homework Statement This is more like a design problem, I'm to evaporate water at 20°C and 2000 psi(Tsat=335.472°C), I have the heat flux the water is going to absorb during heating, and If that flux remains constant during all the length then, how can I find the surface temperature for the...
  50. R

    Distortion in water stream

    I observed something which I've never seen before. We left the tap open and the water stream was flowing in a particular pattern. When we placed a beaker under the water stream, the pattern disappeared. And the pattern itself was oscillating. Here's the video link. Below the the photos of the...
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