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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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16
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5answers
37k views

Is pure water very corrosive?

In other site, someone claimed that pure water is very corrosive. Water distilled for some laboratory uses (like the Z-pinch reactor) is distilled to 0.00000009% purity, and is caustic enough to ...
-1
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2answers
47 views

Equation of water at triple point

I was thinking about what exactly happens at the triple point of water, and what could be the effect of adding solutes/solvents. I feel we can represent the triple point using the following ...
-1
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0answers
28 views

Homework - Water evaporation in a sealed container with vacuum [closed]

Let's say I have a container where I extract the air and create a near perfect vacuum. The volume of the container is 100 m^3 In the container there is a large bottle (made of glass) which is filled ...
0
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2answers
42 views

Does ice increase the humidity of its surroundings? [closed]

Does ice increase the humidity of its surroundings? I'm trying to use the BME280 for an Arduino project regarding locating ice, but I don't know whether the atmosphere is more humid around ice. I'm ...
0
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1answer
44 views

Is it more energy efficient to desalinate seawater by flash boiling or by flash freezing? [closed]

In Saudi Arabia I think there are two types of desalination using flash boiling from electric power production and also from flash freezing using solar absorption refrigerant freezing. One requires ...
11
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1answer
285 views

What might serve as an initial starting photocatalyst for this large water-splitting solar simulator?

Question: What might serve as an initial starting photocatalyst for this large water-splitting solar simulator? Surely there must have been some planned experiments! The Gizmodo article Insane Light ...
-2
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0answers
32 views

Is OH– a weak base or a strong base? [closed]

From my point of view, $\ce{OH–}$ should have been a very good base, but in my copy, it is written that $\ce{OH–}$ is a weak base. All the articles that I can find on the internet do nothing but ...
3
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1answer
2k views

Why is ammonia less acidic than terminal alkynes?

Here's a picture from Organic Chemistry by Solomons, Fryhle & Snyder : Why is it that ammonia is less acidic than terminal alkynes even though water, and even alcohols, are more acidic than them?...
0
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1answer
20 views

Using charcoal to clean water [closed]

I have read about charcoal being used to clean water before it is then boiled or mixed with a UV light stick. I have some questions about this: 1) Does it have to be activated charcoal? 2) Can ...
1
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2answers
1k views

Is there a treatment for distilled water to become drinkable? [closed]

It is my understanding that, drinking distilled water may not be recommended. Its not recommended indeed. Or maybe its not not recommended... Maybe not not indeed........ Anyway.... Well, apparently, ...
0
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0answers
11 views

Electrolysis of water and Gibbs Energy

I'm writing a chemical equilibrium program which minimizes the Gibbs energy. The program accepts as input the total amounts of the elements comprising the system, and a list of possible molecular ...
12
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1answer
4k views

Is the equation pH + pOH = 14 valid at different temperatures?

$\mathrm{pH} + \mathrm{pOH} = 14$ For water at 60 degrees Celsius, $K_\mathrm{w} = 1 \times 10^{-13} = [\ce{H+}] \times [\ce{OH-}]$ Hence, $[\ce{H+}] = 1 \times 10^{-6.5} = [\ce{OH-}]$ So $\...
0
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1answer
35 views

Is there a temperature where salt doesn't dissolve in water?

I know that salt dissolving in water is driven mostly by entropy. However, at lower temperatures, entropy is less of a factor in controlling reactions. Is there a temperature where salt doesn't ...
0
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2answers
76 views

Does water in big cities get heated (boiled) for treatment?

I live in Bangkok and read how water comes to customers here: I understand from the chart that water go through Thon Buri treatment plant (west Bangkok) and Mahasawat treatment plant (east Bangkok) ...
1
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5answers
285 views

Numerical related to crystallisation of water below its freezing point

Question: There is $16\ \mathrm g$ of pure water in a container at temperature $-20\ \mathrm{^\circ C}$. A small piece of ice is added to start crystallization. Amount of water in container when ...
6
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4answers
13k views

Why is a tin can that appears like galvanised steel rusting?

I bought a canned pineapple and finished the content. The part of the can that is in contact with the liquid appears like galvanized steel (crystalline surface or spangles sort of appearance), while ...
1
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3answers
72 views

Tap water pH adjustment using citric acid

I've lowered tap water pH from 7 to 6 using citric acid. After couple of hours pH raised again to 7. What is the reason for this raise? Citric acid overcomes waters buffering feature then raise the $...
2
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1answer
208 views

How do I convert this ion exchange capacity into water softening capacity?

I am researching for an extended experimental investigation into methods of water softening. One such method is the use of ion exchange resin. I have contacted the supplier of the resin for its ...
5
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1answer
1k views

How does ice melt?

I know that when water freezes, it forms a crystalline structure created by the hydrogen bonds between polar water molecules. Also, I know that during a phase change, the potential energy of the ...
14
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6answers
3k views

Is there a simple field test for heavy water?

Thought experiment Given two glasses of water, how would one detect which glass contains heavy water, and which contains potable water without using complicated laboratory equipment? Something like ...
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1answer
30 views

What formula allows adjusting balance of (Ethyl Alcohol / Water / Caffeine powder) to know concentration for the Caffeine solution?

I am experimenting with different levels of concentrated caffeine solution. The solution has a small percentage of ethyl alcohol, in the $\ce{H2O}$. Problems encountered too much ethyl alcohol ...
2
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1answer
660 views

Can water volume reduce with introduction of another chemical [duplicate]

Can a chemical be introduced to a volume of water which can actually reduce the volume of water in that container?
14
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1answer
12k views

If electrolysis splits water, why does only either hydrogen or oxygen (but not both) bubble up on one pole?

If electrolysis splits water, then that means that $\ce{H2O}$ is split into $\ce{H}$ and $\ce{OH}$ or $\ce{O}$. How come that if a water molecule is split at e.g. the negative pole (anode), only the ...
5
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0answers
187 views

Why does pKw first decrease but eventually increase when temperature rises?

I understand the initial decrease in pKw. $\ce{Heat + H2O (l) <=> H+ (aq) + OH- (aq)}$ Temperature increases, reaction shifts to the right, so $\ce{H+} \text{ and } \ce{OH}$ ...
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1answer
32 views

Copper wire smoking underwater [closed]

I am doing an electrolysis experiment with two copper wires inside of test tubes that are both submerged underwater, with 20 V per wire. Test tube A is creating oxygen gas at a high rate, but test ...
0
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0answers
18 views

Method to find out the amount of solvent replaced by another solvent

So I am performing a relatively simple coprecipitation experiment to synthesize ceramics. All my precursors are in aqueous solutions. But due to the high surface tension of water, drying the water is ...
3
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0answers
51 views

Thermal decomposition of steam to hydrogen and oxygen; at what temperature is half decomposed and how to calculate?

In comments below this answer in Space Exploration SE I've said: (Wikipedia) says that dissociating water costs about 4.4 eV per bond. If 𝑘𝐵𝑇= 4.4 eV and $k_B$ is 8.617E-05 eV/K then that ...
6
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4answers
9k views

When our hard water is boiled, it leaves a blue-green residue in our kettle.

The inside of our kettle is lined in a blue-green deposit. Our water is very hard, but what minerals could cause the coloration?
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0answers
10 views

Ionic content of different samples of water

So I was reading about impurities of in water and I have a question in mind: So say we have Distilled Water , Deionized Water , Tap Water and Soft water which was softening using dowex resin or any ...
1
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5answers
6k views

Does the electrolysis of water produce chlorine gas?

http://orbitingfrog.com/2014/11/02/electrolysis-of-water-with-pencils-and-a-9v-battery/ This article seems to indicate that "a small amount of Chlorine may be produced as you [perform electrolysis on ...
5
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1answer
875 views

Is there a food-safe hydrophobic liquid with a substanially higher density than water?

Requirements In short, I am looking for a fluid that meets these criteria: Hydrophobic Denser than water Low viscosity Food safe Background We are working on adding a pool and designing a backyard ...
12
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2answers
3k views

Would sodium explode in salt water?

I’ve seen the video etc of sodium being put into freshwater and the reaction of flames/small explosion but I wonder if the same reaction would occur if conducted in salt water such as the ocean.
1
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1answer
55 views

Precipitation of water-insoluble materials from shower or laundry greywater

I am currently working on a project to build a filter that aims to separate or salt out the 'dirt' in shower or laundry greywater. The ideal result from this chemical reaction will be such that the '...
0
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1answer
34 views

Order of magnitude of ions in water [closed]

My book says water has approximately $\pu{3.35E28 molecules/m^3}$ and that only a small part of water molecules are dissociated to $\ce{H+}$ and $\ce{OH-}$ ions and that the approximate amount of ...
4
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2answers
2k views

Plastic membrane that lets water in from the outside only?

I'm looking for a type of plastic membrane that would let water through it from the outside, but wouldn't allow water to escape once it's inside the membrane. Ideally available in a roll. Does such ...
1
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1answer
63 views

Temperature and pressure for three phase equilibrium of aqueous sodium chloride solutions

I am currently investigating the effect of adding Salt(NaCl) to water on its triple point. Let us assume the mass ratio of water to NaCl is $1:1$. I asked a similar question previously. But, I still ...
0
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1answer
177 views

How to dispose of NaOH solution? [closed]

I have a range of sodium hydroxide solutions with different concentrations. (from 1.0 mol dm^-3 to 0.5 mol dm^-3). The max volume of each is 100ml. How can you easily dispose of these? Can I pour them ...
0
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0answers
42 views

How to calculate Revelle factor using only pH, DIC and TAlk for seawater?

I have the temperature, salinity, $\mathrm{pH},$ dissolved inorganic carbon (DIC) and total alkalinity (TAlk) values for an estuarine water sample. I want to calculate the Revelle factor. The Revelle ...
7
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2answers
1k views

Is water stream deflecting in an electric field really based on water's polarity?

A common highschool chemistry example for the polarity of water is the experiment where stream of water is deflected under the influence of a charge (electric field). Now I have come across some ...
10
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2answers
11k views

Why does water volume decrease when salt is added? [duplicate]

Why does water volume decrease when salt is added? Our teacher asks us in the class but I don't find any strong reason.
-1
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1answer
30 views

Is an ion or a polar molecule more attracted to water in general? [closed]

I realize that there are exceptions but as a general rule of thumb, is an ion or a polar molecule attracted to water? I think that it would be ions since the charge is much larger than the net dipole ...
-2
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2answers
63 views

Ratio of Water to Isopropyl Alcohol? [closed]

I am looking for a very simple formula to calculate the ratio of water to 99% isopropyl alcohol that I need to prepare a solution with a density of 0.925 g/cm3. I am assuming there is one.
4
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2answers
544 views

How much water vapour can a gram of Uppsalite absorb at NTP?

This site states: It turned out that Upsalite had the highest surface area measured for an alkali earth metal carbonate; 800 square meters per gram. Assuming that a sphere may enclose the maximum ...
0
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0answers
20 views

Could silica aerogel withdraw water from sulfuric acid?

Both silica aerogel and sulfuric acid have a hygroscopic nature. Which of the two is the strongest ? Could silica aerogel withdraw water even from concentrated sulfuric acid ?
0
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2answers
70 views

Finding pH of acid in water [closed]

How would you find the pH of an acid dissolved in water? Would you need to take the fact that the pH of water is already 7 into account and go on from there? Say, for example, that you add 0.0500 mL ...
2
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3answers
4k views

Can you make deuterium-depleted water through a freezing method?

Deuterium-depleted water (DDW) is sold commercially by some companies. It is apparently manufactured by fractional distillation, which leverages differences in boiling points of heavy and light water. ...
5
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1answer
4k views

Why is lemon mixed with water considered alkalizing water?

The benefits and facts of alkaline water are often skewed due to the marketing of companies and uneducated hype for the innocent idea of unlimited potential. I wanted to know the specific reactions ...
0
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0answers
33 views

Factors affecting hardness of water - EDTA titration

I am thinking of doing a project involving EDTA complexometric titration to determine the hardness of the water. I am not sure if the pH will affect the hardness of the water. If it did, I would ...
6
votes
3answers
1k views

Can a reverse osmosis system remove radioactive elements in contaminated water?

I am curious to know if a reverse osmosis system can clean water from radioactive elements like cesium-134 and cesium-137. If it can, how efficient can it be?
0
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1answer
55 views

Is there any difference between thermal energy at room temperature in fluids(water) vs air?

Context of the question: I was reading on hydrogen bonds, specifically how close they are to the thermal energy of the fluids. So I googled the value of thermal energy at room temperature, which was $\...