For questions relating to water (H2O), specifically its structure, properties, and uses in chemistry.

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4answers
168 views

Is Cold water heavier than hot water?

I have come across this Quora Answer where it was written that cold water is heavier than hot water. Are there any proofs which support it?
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0answers
24 views

What is the formula for Boiling Water and Frozen water ?` [on hold]

I always wanted to know if there is a difference between the temperatures of chemical elements. I know water is Ho2 warm or cold but the molecules which are frictional to bring the water to boil or ...
-2
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0answers
43 views

Calculate the Concentration of HCO3^- and CO3^2- [closed]

Surface water in an open area of the Indian Ocean adjacent to Kenya has an alkalinity of $2320~\mathrm{\mu equiv/L}$ and a DIC concentration of $2.03 \cdot 10^{–3}~\mathrm{mol/L}$. Calculate: ...
0
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0answers
15 views

Is the water in hydrated salts held in place by a type of bond? [duplicate]

See title And if so, what type? If not, why does the water stay in the salt? (I wanted to add salt as a tag, but I need 300 reputation for that. Could someone higher up please add that tag? I think ...
0
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1answer
42 views

Acceptable levels of HCl?

For a science/engineering project we are taking pool water (disinfected), filtering to 0.1 microns, and pumping to the kitchen. Of course there is still 5 ppm of chlorine present so we want to ...
4
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1answer
31 views

What is the difference between carbon and charcoal filters?

I'm confused about the difference between carbon and charcoal filters. Ultimately, charcoal contains carbon but I have come across an exam question that asks for their individual roles in a water ...
9
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0answers
93 views

There's a ghost in my whiteboard?

...or at least I thought so, when I saw that the ink that was on my whiteboard last night became really messed up the next day. The image below shows my whiteboard before (on the left) and after (on ...
0
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0answers
6 views

Fluoride Solubility in Autoclave Water

if an autoclave contains a component which has remnants of fluoride ions after an acid wash, what temperature/pressure of autoclave would be best to flush out the remnants and ensure the component ...
2
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2answers
31 views

Is water “hardness” dependent more on calcium or magnesium?

If one sample of water has a certain concentration (g/L) of calcium ions, and another sample as that same concentration of magnesium ions, will one solution have a greater "hardness than the other"? ...
0
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0answers
13 views

superhydrofobicity and friction coefficient ?

I learned about superhydrofobic surface like instance water on glass which will not attach due to the lotus effect. Which is altering the surface energy and which will cause the surface to have a ...
4
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0answers
33 views

exchanging H2O in buffer for D2O - pH vs pD?

I have TBS pH 7.4 buffer that I am exchanging all the water out for D2O. How do I find out what the pD is after all the water is gone? I understand that pH meters don't work for deuterium, and it ...
3
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0answers
22 views

Is there a chemical treatment for pipes to reduce or eliminate leaching of lead into tap water?

Given events in Flint, Michigan, where a switch to acidic river water in the city water supply resulted in leaching of lead into tap water from the insides of pipes, I wonder -- has anyone has heard ...
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2answers
157 views

Sensitive test for lead in water?

Some of my friends are in Flint and I'm horrified by their situation. I would like to learn how to test for lead independently. After all if you can't trust the state sending them water to test is ...
3
votes
1answer
59 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 ...
0
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0answers
29 views

Soluble or insoluble?

In the picture attached here, is the compound in water soluble or insoluble? I get confused while identifying solubility of a solute in a solvent when a situation like this arrises. The crystals of ...
0
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0answers
34 views

How much energy does it take to produce water from talc?

Given talc, $\ce{Mg3Si4O10(OH)2}$ which can be disolved in a strong acid with water to produce $\ce{Mg3Si4O10(OH)2 +6H+ + 4H2O -> 3Mg^{2+} + 4H4SiO4}$, what can be done to produce more water than ...
3
votes
3answers
110 views

Sodium chloride and melting of the ice

My question is this, In European countries, they use NaCl or KCl to melt ice during the winter season. In Asian Countries, they use NaCl to keep the ice without melting. (Ex- Ice cream boxes, Beer ...
0
votes
1answer
52 views

What makes these particles hygroscopic? [duplicate]

Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment. For cotton there is capillary action. Hydrates like KOH attract water due to lower ...
5
votes
1answer
63 views

Could a safe water ocean exist on a world with predominantly chlorine atmosphere?

I am researching for a Si-Fi book. Would a water ocean on a world with a predominantly chlorine ($\cf{Cl2}$) atmosphere be safe to touch? Would the chlorine over time saturate the water creating a ...
2
votes
2answers
65 views

How does one determine the probability of H⁺ to H₂O in pure water?

The ratio of $\ce{H+}$ to $\ce{H2O}$ is something around $10^{-8}$. How did people determine that? You cannot use the $K_\mathrm{w}$, $\mathrm{p}\ce{H}$, $\ce{[H+]}$ ion concentration value to answer ...
0
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1answer
33 views

Does autoionization occur in steam?

It is well known that H2O spontaneously autoionizes to H+ and OH- when it is in liquid phase. I was wondering whether it does the same in gas phase, either to the same extent as in liquid phase or at ...
5
votes
1answer
51 views

Does the salt in the ocean act as a binding agent on sand?

When I walk on the beach, there appears to be an upper layer of the sand that is 'crusty'. This appears to be the opposite of what you see in sand in a dessert setting, where the individual ...
2
votes
1answer
38 views

Why does ozone have such a large solubility in water?

At $25~\mathrm{^\circ C}$, the solubility of ozone is $109~\mathrm{mg~L^{-1}}$. This is $13$ times higher than the solubility of diatomic oxygen. What causes this?
4
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2answers
45 views

Will freezing water still expand width-wise in a pipe (possibly breaking it) if it's free to expand lengthwise?

Will freezing water still expand width-wise in a pipe (possibly breaking it) if it's free to expand lengthwise?
3
votes
1answer
47 views

Can gaseous hydrogen and gaseous oxygen be compressed without reaction?

I'm looking into building a clean Bunsen-style burner (or rocket engine - I haven't decided yet). I will be using electrolysis to extract hydrogen and oxygen from water, but the apparatus I am ...
3
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0answers
26 views

Behaviour of oleophobic and hydrophobic object in an oil and water solution

I am wondering what would happen if I put a small (between $\mathrm{5mm}$ and $\mathrm{1\mu}$, density between $\mathrm{1}$ and $\mathrm{2\: g/mL}$) item with both oleophobic and hydrophobic ...
5
votes
1answer
179 views

Can we break the covalent bonds of water molecules using resonance frequencies?

Can we break the covalent bonds of water molecules $\ce{H2O}$ using resonance frequencies? What is the wavelegth of the water's molecule? Can we create a vibration like this and use it to separate ...
3
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2answers
80 views

Is Hydrolysis same as dissolution?

I have book that contains the following paragraph: Due to high dielectric constant, it (water) has a very strong hydrating tendency. It dissolves many ionic compounds. However, certain covalent ...
3
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0answers
16 views

Measuring the effect of increasing salinty on the concentration of Dissolved oxygen

I want to investigate the effect of increasing salinity on the concentration of dissolved oxygen, in a water sample being distilled water. Would that work? My concern is, that since its not a true ...
3
votes
2answers
41 views

How can a sample that is in two different states be at a uniform temperature?

In my chemistry course, the professor has discussed how a sample that contains both solid and liquid water would be at 0 degrees Celsius no matter what the proportion of solid to liquid water is. I ...
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0answers
27 views

Is the reaction between powdered soap and water exothermic?

I have done a fair share of hand washing using powdered soaps and in the first few seconds after mixing the soap with water, I have in most cases felt a subtle warmth in my hands. Is it that the ...
0
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0answers
28 views

Are open system phase transitions physical equilibriums?

I have been told that phase transitions=physical equilibriums. How can phase transitions be physical equilibriums? For example, if you have liquid water going into gas phase, doesn't delta G have to ...
2
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0answers
64 views

Why is calcium stearate (soap scum) insoluble in water while potassium/sodium stearate are soluble in water?

So, potassium and sodium containing soaps work because they have a polar end and a non-polar structure for the rest of the molecule - they can thus be dissolved in polar and non-polar solvents. This ...
6
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0answers
68 views

What is a dry electron?

I was reading about water photolysis which produces a positive water radical and a dry electron, or an excited water $\ce{H2O^{*}}$ through the following equation $$\ce{ ...
0
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1answer
43 views

Why is the ionic product for water $10^{-14}$? [closed]

Why is the reference value of $K_w=10^{-14}\ \mathrm{M}^2$, such that $[\ce{H+}]= 10^{-7}\ \mathrm{M}$ and $[\ce{OH^-}]= 10^{-7}\ \mathrm{M}$ for pure water at $20\ ^\circ \mathrm{C}$? For example, ...
0
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1answer
30 views

Does ethylene glycol sink in water?

I’m a little concerned that there is a far stronger mix of antifreeze in my car's coolant system than I am aware. I check the antifreeze level in my car (using a refractometer) when the engine is cold ...
1
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2answers
51 views

Electrolysis of sodium chloride solution [closed]

I am trying to understand electrolysis. My question is: when electrolysis is done with a NaCl solution I have learnt that sodium metal is not formed. Why is this?
3
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1answer
44 views

Does Dean Kamen's Slingshot really filter virtually everything?

According to Dean Kamen (in the movie http://www.imdb.com/title/tt3242934/) and on the Net ...
5
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2answers
98 views

Why is water not part of the equilibrium constant?

In the acid base reaction $$\ce{NH4+ + H2O <-> NH3 + H3O+}$$ the acidity constant, which is a relation between concentrations is given by $$K_{\mathrm{a}}=\ce{\frac {[NH3] \cdot [H3O+]}{ ...
15
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2answers
2k views

What makes ice slippery?

I've heard and read (multiple times) two theories have have been around for a while, both of them obvious nonsense. One states that pressure and friction make the ice melt (turn to water) where the ...
1
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2answers
29 views

How to create different fluorescent colors using household items

This is a request: I wanted to create fluorescent liquids that have different colors. I'm going to dye my flowers in different fluorescent colors and I'd need a recipe for fluorescent colors that ...
-1
votes
1answer
63 views

Has the exact formula for computing the density of water in terms of temperature ever been determined?

According to a simplified quantum mechanics theory where electrons and nuclei are point charges and there's no nuclear chemistry, and the gravitational constant and cosmological constant are zero, ...
0
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1answer
29 views

Is there a way to liquefy a super absorbent polymer without using salt?

I understand that once a SAP absorbs a liquid it becomes a type of gel and that this gel can be liquefied by applying salt, are there other methods to liquefy this gel without using salt?
6
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2answers
100 views

Estimation of the bond angle of water

We know from experimental data that $\ce{H-O-H}$ bond angle in water is approximately 104.5 degrees. If its two lone pairs were bonds (which is unfortunately impossible) also $\ce{O-H}$ bonds and a ...
0
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1answer
32 views

Action of NaCl in different conditions [closed]

$\ce{NaCl}$ is used as a freezing mixture in ice cream, while the same $\ce{NaCl}$ is used for melting of ice on roads (as a sweeping agent for ice). Discuss its mechanism.
3
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0answers
62 views

Specific Heat Capacity of Heavy Water

Water has an unusually high specific heat capacity due to it's hydrogen bonds. Why is it that the change in isotope causes a 10% difference in the heat capacity? How does the added neutron in the ...
1
vote
1answer
22 views

What electrodes to use to minimise corrosion during water electrolysis?

I did the $\ce{H2O}$ electrolysis experiment a few times, but every time a huge amount of the oxygen reacted with its corresponding electrode. What material should the electrode be made of in order to ...
0
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0answers
12 views

What are the by-products produced by electrolysis?

Say I have two copper plates in 8L tap water with 1/2 cup of salt added at room temperature. The voltage applied is 12V from a car battery. What chemicals will be produced in the water as a by ...
0
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1answer
28 views

What [if anything] is special about the boiling process of purifying water (excluding temperature)?

I know that water boils at $100~^{\circ}\rm C$. I also know that the standard way to purify water is to boil it for roughly a minute. What I'm curious about is, what properties of the boiling process ...
0
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0answers
31 views

Can we modify plastic to cool things?

I have very little chemistry background and I have a project that I'm working on about smart plastics. My question is: Can you chemically modify plastics so that you can make it into a regular ...