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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Methods to quantify lead(II) concentration in water on the ppm/ppb level

While there are several ways to quantify metal concentrations in water, a lot of them are only specific to select metals. For example, there is the Orthophenanthroline method for quantification of Fe (...
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can a vapour denser than air evaporate in a closed chamber?

Imagine a closed container filled with air. There is some liquid substance on a bottle placed on the floor of the container. Let's heat the liquid until it starts to evaporate. Let's say 20% of the ...
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Boiling Soda Reaction - Does It work? [closed]

I've come across a series of reactions, where $$\ce{2NaHCO3 <=> Na2CO3 + H2O + CO2}$$ at temperatures above 50 degrees Celsius, and $$\ce{Na2CO3 + H2O <=> NaHCO3 + NaOH}$$ I Have 3 ...
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Does anyone know a database that shows the effect of electrolyte concentration on the production of hydrogen gas during electrolysis of water?

I'm currently studying in the International Baccalaureate model. This high school model asks their students to do an individual work called the Internal Assessment. One of the subjects I study is ...
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2answers
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Concentration when done wrt mass or volume [closed]

I have a question asked in jee main 2020. 10.30 mg of o2 is dissolved into a litre of sea water of density 1.03 g/ml. The concentration of o2 in ppm is? Well I know that ppm is generally possibly ...
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Why is the ionic product of water $K_w$ the same in acid, water, and alkali?

Seen on the web: The concentration of [H+] and [OH−] both vary based on the the composition (acid/alkaline) of the solution, but the remarkable thing is that their product does not. When [H+] goes ...
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1answer
34 views

Auto-ionization equilibrium of water shifted with acid-base addition? [closed]

Adding acids or bases to water, so that either pH or pOH decreases independently of the other, will that affect the auto-ionization of water? For example, pure water + auto-ionized state, with some ...
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Is there a difference between hand soap and body soap with killing viruses? [closed]

With the Coronavirus in full swing around the globe, I wanted an answer to this, particularly since my dad has just been diagnosed with Leukaemia. We can't find hand wash anywhere but instead I just ...
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Intermolecular Forces of Attraction [closed]

Imagine a bottle 85% filled with water and the rest is just air, and the cap is closed. Here are now my questions. Since the cap is closed completely, the air bubble is formed. Is that air bubble ...
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How does hydrogen peroxide affect the redox potential of water?

I work in water treatment and we use hydrogen peroxide $(\ce{H2O2})$ to treat levels of ferrous iron and help our coagulant (aluminum sulfate) react better to clump solids. We’re told that generally ...
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How to dissolve magnesium malate in water? [closed]

When I mix magnesium citrate with hot water, it quickly dissolves and the water becomes transparent. When I do the same with magnesim malate, it does not dissolve, it sinks to the bottom as sand. ...
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Lowering water hardness using Ion exchange method [closed]

I want to remove water hardness using Ion exchange resin filter. Does anyone tried this method I want to know if this method really lowers the hardness. What is the best method of regenerating resin ...
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1answer
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Concentrating mixtures of volatile compounds

My interest is primarily food-related here but I think this is a fairly general chemistry question. Let's say I took some liquid like lemon juice and ran it though a rotary evaporator to get just the ...
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What happens to the crystal structure of ice as it gets colder and colder [duplicate]

Not sure if this belongs on Chemistry or Physics stackexcahnge. As water freezes into ice, it turns into a solid, and expands as it forms a crystal structure. But what happens to this crystal ...
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What is the essential difference between distilled water of different distillation levels? [closed]

Although not a chemist I often read that different liquids made of molecules with enough low molecular weight and enough strong chemical bonds can be distilled by this process: The liquid (say, water)...
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Density of water increases from 273 to 277 K due to increase in entropy?

In a set of questions that I was solving, the answer to one of the questions asking why the density of liquid water increases from 0 to 4 degrees C had the above answer: due to an increase in entropy. ...
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2answers
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Figure out how many deuterium atoms in a 3 microgram ice core sample

I'm in an introductory Chemistry class and ran into a Pearson problem, that no-one in our class including our professor has been able to truly figure out. I know the solution is $4.69 \times 10^{13}$...
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1answer
33 views

What causes the differences in price in home testing kits for lead in water? [closed]

The price differences between home testing kits to test tap-water for lead are huge. 20 dollar will either buy 1 test kit or 100 test strips. Both are intended to test drinking-water safety. What ...
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52 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 ...
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2answers
51 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 ...
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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 ...
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1answer
21 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 ...
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1answer
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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 ...
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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) ...
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3answers
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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 $...
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1answer
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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 ...
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1answer
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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 ...
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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 ...
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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 ...
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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 ...
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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 '...
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1answer
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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 ...
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581 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 ...
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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 ...
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1answer
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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 ...
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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.
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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 ?
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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 ...
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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 ...
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Why are wet things harder to ignite than dry things? [closed]

Specifically wood and paper and other hydrocarbons, but not necessarily excluding other things that burn. We all know wet wood is very hard to ignite. Wetness here refers to water. But why is that ...
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Liquid alternative to alcohol to lower density of water

I am trying to create a suspension of polypropylene particles in a water based liquid. I want the density of the liquid to be more than or equal to the density of polypropylene (855 - 946 kg/m3) so ...
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UK - Testing for Tap Water

Water is pooling in my garden next to my neighbour's fence. He has been harassing us in multiple ways for 8 years. It is the only place on my property where this is happening. It has never happened ...
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1answer
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Boiling point elevation does not depend on the solute? [closed]

I've recently carried out an experiment trying to measure the boiling point elevation of water after adding 5M of NaCl and KCl. Although for some reason, KCl solution started boiling around 90 degree ...
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Are all volatile liquids combustible?

I realized that liquids like petrol, kerosene and even perfumes are combustible when they are volatile. Could that be the reason why water is not combustible is because it is not volatile? Are ...
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1answer
383 views

Why does boiled water have a different taste as compared to cool water? [closed]

I have noticed it frequently and decided to check with some of my peers and friends about this and they too have felt such a thing. The taste comparison occurs after the boiled water is cooled down to ...
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1answer
59 views

Ventilating combustion byproducts in water heaters

I'm designing a system which will heat up water by burning natural gas which is commonly available. I would like to have a slow flame because water will need to reach $\mathrm{70^\circ C}$ and stay ...
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1answer
740 views

Will charcoal briquettes (not activated) absorb water out of the air in the house in a subtropical climate?

I live in Florida, an incredibly wet environment where it's very difficult to get moisture out of house without using a dehumidifier 24/7, which is too expensive. Would charcoal briquettes be of any ...
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862 views

Is Phosphate (PO4 3-) solube in water? [closed]

Josh~ Superphosphate is used instead of just phosphate because superphosphate is a compound whereas phosphate is an ion. This means that phosphate must attach itself with a cation in order to give a ...
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4answers
411 views

Dissolving sand (or something similar) in a bottle of water?

I would like to create an illustration to demonstrate something during a talk. The idea goes that there is sediment in a bottle of water that sits at the bottom until shaken up then adding another ...
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Does water really have strong EM absorption at 3 kHz in solid and 2 GHz in liquid? Why the huge shift?

While writing this answer to the question Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement I ran across this large PDF file of a book Soil and Environmental ...

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