Questions tagged [water]
For questions relating to water (H₂O), specifically its structure, properties, and uses in chemistry. For questions not about water but rather about solutions in water, use tags [aqueous-solution] or [solubility] instead.
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Is wetting tissue paper an exothermic process? [closed]
I have noticed if I hold a tissue paper in my hand a sprinkle a few drops of water over it with my other hand, it becomes slightly warmer in the places where it is wet for a few seconds. The effect is ...
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Is there a supercritical state for ice?
I know there is such a thing as a supercritical fluid, where the vapor and liquid phases are indistinguishable, but is there such a thing as a supercritical state for ice? Another way of asking this ...
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Dewpoint of water in relation to composition of atmosphere
A couple of colleagues and I were talking about the nature of dewpoints, specifically the dewpoint of water in relation to the chemical composition of the atmosphere in a closed space.
If I remember ...
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How can the Kw of water be constant?
I know in neutral solution, $\ce{[H+]}= \ce{[OH-]}= \pu{1.0 x 10^-7}$.
However, let’s say I add an acid like HCl. This will increase $\ce{[H+]}$, therefore it’s no longer $\pu{1.0 x 10^-7}$, but is ...
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Where does the ionisation energy for a reaction to take place comes from? [closed]
Can anyone tell me exactly what happens during a chemical reaction in terms of ionisation energy? I know that during a reaction there is an exchange of electrons (except for those where electrons are ...
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Validity of ideal gas law for pure species or mixture
I'm currently dealing with an application involving gases. I have pure nitrogen as a pressurizer and eventually water vapour (only if condition for evaporation or boiling are met).
I wanted to ask to ...
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How does a dry shampoo work?
From my chemistry knowledge, I know that soaps are made from fatty acids and some sort of base and this reaction also gives us $\ce{H_2O}$ so the grease in hair dissolves and gets washed away in water....
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Why is octane more volatile than water while having a higher boiling point?
Octane has a boiling point of 120 °C. Water has a boiling point of 100 °C. The definition of boiling point is, "the temperature which the liquid substance's saturated vapor pressure equals the ...
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Closed pressurized water vessel
Suppose we have a closed container not isolated from the external environment so that heat exchanges can occur on the lateral wall (mainly for convection). The water inside is pressurized by a gas (...
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Can “hydrates” of crystals form with other molecules?
It is well known that copper sulfate, sodium sulfate, et al crystallize with 5,10 water molecules of hydration, locked in their crystal lattices. Is it possible to have other molecules instead of ...
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Understanding the Role of Gibbs Free energy and Enthalpy as the energy required to drive a reaction
I was looking at the enthalpy change for water-splitting reaction:
$$ \Delta H^o_R = [\Delta H^0_{H_2(g)} +\frac{1}{2}\Delta H^0_{O_2(g)}]-\Delta H^0_{H_2O(l)} = \pu{285.83 kJ/mol}$$
According to ...
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How does MeOH absorb into polypropylene?
Currently working on a project where we want to functionalize PP membranes with various monomers. Our chemistries are aqueous and have therefore not been compatible with the membranes. The work-...
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How to correct for acidic water when taking the pH of a soil/water solution?
I work in a soil science lab and not very much a chemist.
Recently I took the $\mathrm{pH}$ of a large number of soil samples using a glass electrode on a mixture of $\pu{10 g}$ soil and $\pu{20 mL}$ ...
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Is a Sodium Chlorite Product Safe for Car Odor-Removal? [closed]
I would like to ask the science community's opinion about the safety of sodium chlorite for use as an odor-eliminator in an automobile's interior.
While the ingredient in the product is sodium ...
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Why my mineral water from different sources do not mixed well? [closed]
Background:
In 8 hours range, I have bought cold mineral water (brand A), then refill the plastic bottle with cold mineral water (brand B) from my office. As far i know, brand B has high pH while ...
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Calculating salinity from sodium and chloride in water [closed]
let me start by saying that I am definitely no chemist, so this question might (or might not) seem trivial to all you professionals out there.
I have recently found a brand of carbonated water here in ...
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How can i preserve a coating of baked in powder on activated carbon pellets whenever it rains? [closed]
I'm trying to create pellets of activated carbon that have a coating of a soluble white powder. To make this I first dissolve a significant amount of this powder in boiling water to the point where ...
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How do the ions in electrolytes lead to lower dielectric constants compared to pure water?
I am interested in the salts used in the gel electrophoresis buffers. As I understand it, one of their roles is to change the conductivity of the medium, because otherwise the electric field would be ...
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What is the effect of dissolving ammonia in water on hydrogen bonding?
Hydrogen bonding exists between $\ce{NH3}$ molecules. When $\ce{NH3}$ is dissolved in water, I know that hydrogen bonds are formed between $\ce{NH3}$ and $\ce{H2O}$ molecules. However, do the $\ce{NH3}...
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At what temperature is bismuth the densest?
Both water and bismuth have denser liquids compared to solid forms, and we know water is the densest at the temperature of about 4°C.
Does the same thing apply to bismuth? Of course, I know the ...
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What equation can be used to determine the mass of water evaporation over time, when cooking?
When baking, cooking or writing recipes, it would be useful to have a ballpark estimate of evaporation rates. This question asks about water, although the answer would ideally include an ...
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What is the osmosis equilibrium point of water beads (for plants)?
In theory, water beads for plants take in water when immersed in it to gradually release it to the roots of the plants. This process happens through osmosis. When the relative humidity is high enough, ...
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What could be the origin of a persisting distorted water NMR signal?
I am currently running some solvent suppression experiment on water samples. I first run a one scan 1H experiment to get the ''O1P'' and then implement it in the solvent suppression experiment (''...
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How does an equilibrium move when increasing the concentration of water?
I have the following equilibrium given:
$$\ce{[Co(H2O)6]^2+(aq) + 4 Cl-(aq) <=> [CoCl4]^2-(aq) + 6 H2O(l)}$$
(I imagine the (l) for water is wrong, as the water is a part of the solution)
The $\...
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Diagram of the electric field potential around water
Is there diagram of the electric field around a water molecule. I have seen some simplifications that treat hydrogen as a positive point source and oxygen as a negative point source. But I am looking ...
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Is the common way to calculate the pH of a solution with low concentration of acid wrong? [duplicate]
We had a chemistry test and one of the questions was this:
What is the pH of $1,4^{-8} M$ $HCl$ in water?
This is such a small amount of acid that you need to take into concideration the self ...
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Does "brine rejection" happen for dissolved gases as well?
"Brine rejection" is the effect of sea ice pushing out dissolved salts, forming sweetwater ice and brine. I understand "freeze distillation", a method to concentrate alcohol in ...
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Why does H2O appear as spikes in IR of air?
In the IR of air shown below, the region for water at 1500 cm-1 is hard to individually assign peaks due to their "spikey" nature. Is there any specific reason for this or does it just ...
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What happens to the air pressure above water as its heated to and past boiling?
If I put a pressure sensor inside an airtight container half-filled with water, and heat the water, what will the pressure sensor read as the temperature increases? Would it linearly increase (black ...
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What is the goopy substance that forms before CaCO3 precipitates?
I do a lab where we mix a solution of sodium carbonate with a solution of calcium nitrate. As expected, calcium carbonate (white solid) precipitates out. However, if the concentration is high enough, ...
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Water vapor in CO2 - a chemical reaction?
I am doing some work on measuring water content of a stream of CO2 at ambient temperatures (25°C).
My question is this: Am I dealing with purely a mixture of gases, or is there some chemical reactions ...
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How does hydrogen and oxygen combine to make water? [closed]
When two hydrogen atoms fuse with one oxygen atom to create a molecule of water, each hydrogen atom donates its single electron to the oxygen atom, resulting in 10 electrons for the oxygen, instead of ...
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"Cleaning" of HNO3 solution using distillation
In many industries, pickling baths are common. These are 10 cubic meter baths containing acid baths that metal components are dipped into prior to surface treatment. When the metals are dipped, some ...
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Water dissociation constant $K_w$ in vapour, or are there charges entities ($\ce{H3O+}$, $\ce{HO-}$,...) in water vapour?
When water is in vapour state, to which degree is there still some dissociation with the existence of charged species like $\ce{H3O+}$ and $\ce{HO-}$? (I would be interested by any reference to ...
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Relationship between grams of root and content in a tea
When we make a tea from a some herb, what exactly is the relation between the weight of the herb/root stepped in hot water and how many grams/milligrams are in the tea.
For context and giving a ...
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How can I measure the energy contained within water vapor?
Let’s say I have a kilogram of water vapor at $\pu{423 K}$. Can I directly measure the energy, contained as heat, within the vapor? All the laws I know depend on knowing the changes that happened that ...
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When we boil water, does the generated steam remain at the same temperature of boiling point until all water is boiled? [closed]
Suppose we are boiling water in such conditions so that the boiling point of water be $\pu{100 ^\circ C}$.
Does the generated steam have the same temperature of 100 C until all water is boiled?
And ...
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Why do stable covalent compounds react with water [closed]
I am curious why a discrete covalent molecular substance, say CO2, would react with water to form an acid, what happens in such a reaction? I'm assuming it has something to do with disassociated ions ...
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Why water volume went up by almost the same amount after adding salt?
Seems like it's a well-known fact that adding salt to water will not raise the water volume by much (e.g.: Why there is no change in water level when salt is added? )
I've done this experiment at home ...
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Putting salt and ice in a can causes frost to form, while doing this again without salt will only cause condensation, why?
If this is the wrong place to ask my question, then blame my friend, and also tell me where to post this since I'm new. Anyway, we did an experiment in class where we took 2 soda cans with no top. We ...
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When hydrogen and oxygen reacts, what defines if it will turn into hydrogen peroxide or water?
If you have a jar with oxygen and hydrogen inside, I'm interested in knowing what variables are most important to ensure that the mixture will become water (if that was the goal) or hydrogen peroxide, ...
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Which water is easier to filter? Rain water or tap water [closed]
I understand the water greatly varies depending on the region and filtration differs as well. Is it better to filter rain water or tap water from contamination like hormones, pesticides, and cloud ...
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Hydrogen bond in water vapor [closed]
As the temperature increases and liquid water changes to gas, are ALL the hydrogen bonds broken or they are just weaker?
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Can deuterium be separated from heavy water via electrolysis? It is an isotope of hydrogen, so I guess it should act in the same way?
I was wondering if it is possible to separate deuterium from heavy water via electrolysis.
Also, is this the way deuterium gas is obtained on an industrial scale, or are there better methods?
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Removing Copper from drinking water by Electrolysis? What to keep in mind?
The drinking water in my flat contains a lot of copper. Although the amount of copper is around the allowed limit 2mg/l I would prefer to reduce it.
I know that it is at this value from a paid ...
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Why do we take active mass of water 1 but while calculating pKa of water as 55.345? [duplicate]
First, I should mention that the question was already asked here:Why is active mass of a pure solid or liquid always taken as unity?
But while calculating $\mathrm{p}K_\mathrm{a}$ of pure water we ...
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Can someone explain the chemistry around adding Isopropyl Alcohol to water contaminated gasoline - how does the IPA 'remove' water from the gas?
So there are many products on the market sold as fuel additives; some (like 'Heet' brand) are nothing more than 99.9% isopropyl alcohol in a nice package.
When trying to understand how they work and ...
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Can magnets boil water with no increase in temperature? [closed]
In this YouTube video an experiment is done with magnets and water. And at 7:14 they claim that the water boils, but with no increase in temperature. Is this possible?
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What is the correct method for converting a concentration given in ppm to molarity?
I need to convert a concentration of dissolved boric acid $(\ce{H_3BO_3})$ in water (at high temperature and pressure) from ppm to mol/L.
Concentration of boric acid: $c_{ppm}=1500\ \ce{ppm}$
Molar ...
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How does the partial pressure of oxygen relate to its concentration in water?
I've read that the partial pressure of oxygen in water will be the same as the partial pressure of oxygen in the atmosphere, but that the saturation of oxygen in water is dependent on factors like ...
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