New answers tagged water
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At the triple point the water system is assumed to be adiabatic. The system has 3 phases, ice from pure water, liquid water, and pure water vapor. The various equilibria are shown below.
Note that the ice floats on the water. So the ice is in contact with both the liquid phase and the gas phase. Furthermore The ice can't cover the whole surface like a ...
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The triple point of water is an example of Thermodynamic Equilibrium, which is explained by Wikipedia as:
simultaneously in mutual thermal, mechanical, chemical, and radiative equilibria
Your equation only covers the chemical facet of this equilibrium and hence is not the correct way of representing total thermodynamic equilibrium. I am also not sure of ...
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It depends on the current humidity.
Water vapor certainly does evaporate from ice, as you can see in a vapor pressure chart. If the humidity is 100%, and the air temperature is the same as that of the ice, then the evaporation and condensation are in equilibrium; i.e. water evaporates as fast as it condenses, so there is no net change in humidity.
However,...
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No. It is the contrary. Water from the atmospheric humidity is condensed on objects whose temperature is 0°C.
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The cheapest way is probably to use the sun, as it is done in Tunisia. In Tunisia, they dig long channels on the beach along the sea. The channels must be long and narrow, and they are filled by sea water. Now the channel is covered by an inclined glass roof. The sun heats the water through the roof, and the steam is slowly evaporated and condensed on the ...
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Activated charcoal cleans water mainly by adsorbing the impurities.
You can also couple normal charcoal with sand and form alternate layers of charcoal and sand and pass water through it. It's a very effective Indian style of filtering water. Nearly all suspended particles gets blocked by the above mentioned filtering style.
You can also convert normal ...
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Solubility is an equilibrium phenomenon, which means that its temperature dependence is a function only of the enthalpy change of the reaction, not the entropy. See the van't Hoff equation for the mathematical relationship.
If by salt you mean sodium chloride, the dissolution in that case is only very slightly endothermic, so the solubility decreases very ...
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As mentioned above, boiling all the wastewater would be incredibly expensive. One technique not mentioned in the other answers is that the wastewater treatment center has portions of infrastructure where the water sits in open air pools for a certain amount of time. The UV rays from the sun kill some bacteria.
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No. Heating usual water would be extraordinarily expensive. In all water treatment plant, all over the world, bacteria are destroyed by adding chlorine gaz Cl2 or similar substances delivering Cl2 when dissolved in water. The bacteria are killed by chlorine. So the customer drinks water containing dead bacteria. It does not hurt.
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The previous answers are good ones. I just want to add a (longwinded) metaphorical picture to help understanding the freezing of water at -20C.
Imagine a tower of bricks (2 x 4 x 8 inches each) about 20 high. It is metastable, but the tiniest push will topple it because gravity pulls each brick to the lowest level. This is a metaphor for the freezing of ...
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The crystallization is an operation that delivers heat, and a good deal of heat. This is sufficient to heat the metastable water form -20°C to 0°C.
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So, for water below 0 degrees to freeze, it must first accept heat from somewhere, to reach zero degrees.
No, water can freeze at lower temperatures, see e.g. https://www.youtube.com/watch?v=Fot3m7kyLn4.
As it freezes, the exothermic process warms up the ice and the surrounding water. The difference in enthalpy between liquid and solid water is larger than ...
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If the water contains significant amount of bicarbonates, part of released carbon dioxide may escape and original bicarbonate is finally replace by the dihydrogen or hydrogen citrate.
$$\ce{ HCO3- + H3Citr -> H2Citr- + H2O + CO2 ^}$$
$$\ce{2 HCO3- + H3Citr -> HCitr^2- + 3 H2O + 2 CO2 ^}$$
So, the final $\mathrm{pH}$ may not differ much from the ...
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Oxygenated tap water is rich in transition metals including Fe and Mn ions. Citric is a source of H+ and a good chelate and can drive a redox reaction in the presence of oxygen and H+ proceeding as follows:
$$
4 Fe(2+)/Mn(2+) + O2 + 2 H+ --> 4 Fe(3+)/Mn(3+) + 2 OH-
$$
There is also a likely metal redox couple equilibrium(s) that can be effective in ...
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Maybe citric acid have had a negligible effect on the pH. Everybody knows that in contact with air, pure water is carbonated by CO2 from the atmosphere. And the pH may go down to 5.5. Later on, the water may loose its CO2, and the pH goes back to 7
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Another answer explains more generally how to interpret the problem. This completes that spoiler:
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