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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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 ...
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White creamy substance (not calcium) observed when boiling water is filtered through coffee paper filter

We have hard water from our well. It is filtered twice before boiling it: by the water filter and with a manual on-the-counter filter. When boiled in a clean kettle a white substance floats in the ...
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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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What chemical changes happen in a factory? [on hold]

I need help with that. I have to talk about chemical changes in factories on my chemistry class.
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352 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 ...
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What would superionic water ice look like?

Phys.org's Giant lasers crystallize water with shockwaves, revealing the atomic structure of superionic ice links to Nature Physics: Experimental evidence for superionic water ice using shock ...
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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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What is deionized water used for in an industrial setting?

I've been working in a quality lab at a major PVC siding plant for the better part of a decade now, and I can't bring myself to ask what we use the deionized water from the cabinet for. It's in a ...
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34 views

To which extent is the function of an RO unit affected by inlet water type?

I want to purchase a Reverse osmosis water filter for my home but the issue is that the source of water supply is not always from a single source and hence parameters/properties of source water may ...
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sparkling whiteish water from kitchen tap [on hold]

My shower drainage was clogged, so after trying mechanically I went to the shop for a liquid to unclog it (sorry im not an english speaker). This liquid contains 5 - 15% phosphoric acid and 85% ...
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Can the light reaction of photosynthesis happen spontaneous in pools of water?

I've just learnt that a part of the photosynthesis reaction is the light reaction, where sunlight is absorbed by chloroplasts, which then excites electrons to higher energy levels, allowing for water ...
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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?
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coffee concentrate and water separated after 2 hours. How/why?

I'm asking because this makes no sense to me and making sure I'm not stupid. I brewed 10 gallons of cold brew concentrate(TDS 12.2) and mixed it with 10 gallons of water. I moved 10 gallons of the ...
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Will sodium thiosulfate react with nitrate and/or nitrite ions [closed]

I am doing nitrate and nitrite quantification in raw water and treated water using a colorimetric method. The manufacturer of the instrument states that water with chloride will interfere with the ...
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Metering Device decreases pressure yet produces saturated liquid?

This question pertains to the change of state of liquid using a Metering Device as the refrigerant enters an Evaporator Coil of an HVAC system: The Metering Device takes liquid and then reduces the ...
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What is the formula for evaporation rate of water?

I did my own research, and according to The Engineering Toolbox,the formula for the evaporation rate of water is as follows: $\mathrm{gh = Θ A (x_s - x)}$ $\mathrm{gh}$ = amount of evaporated ...
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Issue with evaporation rate of water

The evaporation rate of water (kg/s) is given by: $$g = \frac{P}{P_o} AΘ$$ Where $P$ is given in Pascals and $A$ is the surface area (in $m^2$) and $Θ$ is the empirical evaporation ...
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Is there any electronic component to water conductivity?

Answers to Decrease in temperature of a aqueous salt solution decreases conductivity indicate that the electrical conductivity of salt solutions arises from the mobility of ionic species and therefore ...
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1answer
206 views

Can ideal gas law be applied to water vapour? [closed]

How to accurately estimate the molar concentration of pure water vapour at 298 K? Can ideal gas law be applied to water vapour to calculate the molar concentration?
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How do you remove lumps in reagents without contaminating them?

I think desiccating the powdered reagent would help remove lumps (at least in preventing lump neoformation) but would desiccation alone collapse all lumps in a powder (say KCl as it lumps easily), or ...
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2answers
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Does adding solutes to water alter its triple point? [closed]

Does adding solutes to water alter its triple point? If yes, how do we find the new temperature and pressure of this point?
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477 views

Dry water using graphite

Dry water or "powdered water" is essentially a bunch of extremely small water droplets surrounded by $\ce{SiO2}$. Some time ago, I was messing around and mixed some powdered graphite with water. (The ...
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Why is distillation not a viable way to separate ammonia from water?

Since the steam pressure of ammonia is higher than that of water, I would expect distillation to be a reasonable way of separating a mixture of both. However, in industrial applications known to me ...
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Do we consider the dissociation of water when dealing with ion concentrations of a solution?

One mole of hydrated copper(II) sulfate, $\ce{CuSO4 . 5 H2O},$ is dissolved in water. How many moles of ions does the solution contain? 1) 1 2) 2 3) 6 4) 7 The correct answer is 2. ...
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248 views

Reason of dissociation of water molecule in electrolysis

$\ce{H2O}$ molecule is dissociated into $\ce{OH-}$ and $\ce{H+}$ ions on reduction at the cathode in electrolysis. But what happens at the atomic level to $\ce{H2O}$ that proton and hydroxide ions get ...
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Reaction of potassium with water

In general, when we put potassium into water, it will produce potassium hydroxide and hydrogen: $\ce{2K + 2H2O ⟶2KOH + H2}$ However isn't the following reaction also possible? $\ce{2K + H2O ⟶K2O + ...
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620 views

How does chlorine in water evaporate?

Drinking water (e.g. from your home's tap) is spiked with chlorine, for an amount of just some ppm. Purpose of this operation is to kill bacteria, for our health. Background: chlorine in water is ...
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If carbon dioxide is non polar, why does it react with water?

I’ve read in many places that carbon dioxide forms carbonic acid with water since the carbon is partially positive and thus the oxygen bonds with it. But isn’t carbon dioxide in its entirety non polar ...
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60 views

Mechanism of burning of hydrogen [duplicate]

So I was curious regarding a simple chemical equation : $$\ce{2 H2 + O2 -> 2 H2O}$$ You add heat to the system (i.e fire) and you get water vapor. I'm curious of understanding the mechanism, ...
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Why does H2O electrolysis produce O2 on the anode instead of H2O2

If the oxidation of $\ce{H2O}$ produces $\ce{OH-}$ ions and the anode separates electrons from them leaving neutral $\ce{OH}$ molecules, why don't they bind to each other covalently?
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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 ...
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1answer
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What is exactly the pH value of distilled water?

This was asked by one of my students in my class. I know it is the pH of 7, but others say it can be 6.55 pH
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Can caustic soda (sodium hydroxide) be used to dissolve urine odour?

I have an area of artificial grass at home in the back garden and during the summer months, the area emits a smell which I can only think is from the dog's urine when he pees all year long. The smell ...
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Is it possible to raise pH in RO water without Na, Mg, K, Ca, S addition?

Maybe the question in the title is simple (=stupid) and the answer is 'simple No' but I have the urge to ask. Some background, I have an aquarium which I use RO water and I use some portions of $\ce{...
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1answer
689 views

Electric field required to split water into oxygen and hydrogen

Others sources typically say that the minimum voltage required to split water into hydrogen and oxygen is 1.229 V. Overvoltage is typically required in a practical device due to inefficiency leading ...
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3answers
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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. ...
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Why mixing water with ethanol produces heat energy? [closed]

Sorry if I'm asking something stupid but I'm trying to understand where this energy gets from. As far as I could find, it is not a reaction as both chemicals left unchanged, so it might have something ...
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Does coffee have the ability to dissolve less sugar into it than water?

Like water can absorb such and such an amount of sugar, can coffee absorb less as it already has coffee in it.
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1answer
153 views

When it rains, it puddles. Spilled salt cycles between wet and dry with humidity. Is this akin to a phase change?

I have some spilled un-iodized table salt (NaCl). It is very humid where I live, and when it gets very humid for a few days, the salt absorbs so much water that it becomes a puddle of (probably) ...
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What is the range of values of n in [Cu(NH3)4(H2O)n]SO4?

My textbook represents the copper ion as "tetraaminecopper(II) sulfate-1-water", so I assumed that this complex ion has only 1 water of crystallization. Then, in the Wikipedia article, they represent ...
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1answer
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Boil to dry 50 liters water

I would like to find out how long it would take to completely turn 50 litres of water to steam. Let's assume power of 2500 W and the water is already at boil. I am not very scientific so please ...
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DHA’s for tanning and water

I’m trying to make my own bath soak for fake tanning and have run into a road block with DHA’s as they (for lack of a better word) don’t agree with water! Is there a way I can fix this so that I can ...
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171 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 ...
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What happens when para-water ice is suddenly melted?

Background (hydrogen) In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic ...
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152 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 ...
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Degree of Hardness Numerical

To remove the temporary hardness from $5\ \mathrm L$ of $\ce{H2O}$ $5.6\ \mathrm{mg}$ of lime is required. Calculate the degree of hardness due to $\ce{Ca(HCO3)2}$ present in water. My attempt: $$ \...
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159 views

Would the change in enthalpy (ΔH) for the dissolution of urea in water be positive or negative?

To test the properties of a fertilizer, $15.0\ \mathrm g$ of urea, $\ce{NH2CONH2(s)}$, is dissolved in $150\ \mathrm{mL}$ of water in a simple calorimeter. A temperature change from $20.6\ \mathrm{^\...
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Why does energy need to be “compensated” in order for solvation to occur?

I am currently learning about the physical properties of alcohols. I understand that the main intermolecular forces between alcohols and water are hydrogen bonds. When these two are mixed, the ...
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307 views

Cp vs Cv for liquid water @ < 4 °C

I'm looking at a textbook question (Engel & Reid, Thermodynamics, Statistical Thermodynamics & Kinetics, 4 ed, Q3.1) which states the following: The heat capacity $C_{\mathrm m,p}$ is less ...
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Electrolysis of water: Which equations to use? (IB Chem)

There is a list of standard electrode potentials at 298 K from the p. 23 of IB Data Booklet 2016. Which of the following equations (forward/backward reactions), from the two possible ones involving ...