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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1answer
20k views

Determining standard Gibbs free energy for water?

I am dealing with the dissociation of water into its components hydrogen and oxygen and I am trying to determine the standard Gibbs free energies of each component. My professor said if the substance ...
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4answers
10k views

Does heavy water taste sweet?

In this YouTube video from Cody's Lab, Cody claims that heavy water tastes sweet. He does some fairly convincing comparisons but still expresses a little doubt that the effect is real. Has this been ...
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1answer
35 views

Indirectly Measuring Diffusion of NO2 into Water

I am working on a data science project with the central hypothesis is that air-born pollutants can become water-born through diffusion. The example I am using as a proof of concept is $\ce{NO2}$. The ...
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0answers
27 views

Why does ethanol have a stronger cooling effect on the body than water? [duplicate]

Why does ethanol have a stronger cooling effect than water (i.e. it feels cooler when dropped onto one’s hands) even though water has a higher heat of vaporization compared to ethanol? If we drop a ...
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0answers
43 views

Why percent concentration in this example is equal 5.07%? [closed]

I got problem with this one: 0.6 g of sodium was added to $20cm^{3}$ of water. Calculate percent concentration of this solution. Answer: Cp is equal 5.07% Could someone tell me how it is possible? ...
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3answers
110 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 $...
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0answers
7 views

Which interaction is called hydration? [closed]

Which interaction is called hydration? A) eten and water B) ethin and hydrogen C) methane and oxygen D) methane nad chlorine
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1answer
35 views

The electrolysis of tap water [closed]

If there is one question that I have about electrolysis, it is "what would the products of the electrolysis of common tap water". I know that the electrolysis of Distilled/De-ionized water produces H$...
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1answer
37 views

1.0 g of AlCl3 is added to 100.0 ml of water. What would be the resulting pH?

$1.0\ \mathrm g$ of $\ce{AlCl3}$ is added to $100.0\ \mathrm{ml}$ of water. What would be the resulting pH? I think the answer may be $4.022$ but I'm not certain. The reaction wasn't provided but I ...
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2answers
40 views

What's the most effective way to reliably trigger and observe hard water scale buildup at a micro level?

We live in an area that's got some really hard water. It's so hard that it kills most of the fish we try to care for in our aquariums and shrimp?... forget it. While this is sad and challenging for ...
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0answers
14 views

How much juice/liquid do we get? [closed]

Okay so, you make juice out of water and juice concentrate. 15% of the final juice/liquied is 0.75liters of juice concentrate. So how much juice/liquid did we get in the end? Basically the rest 85% ...
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1answer
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Why does hot water eventually turn cold, and why does cold water eventually turn hot?

I get cold water from my tap and put it in my water bottle. Over the day as I drink it, the water looses it coldness and slowly becomes warmer. On the other hand, if I get hot water (maybe I'm sick ...
5
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1answer
11k views

Why is density of water maximum at 4 degree celsius?

Why is density of water maximum at 4 degree celsius? We were having a discussion to this question in class and I could gather the following points. 1) $H_2O$ exists in a cage like structure in ice ...
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0answers
21 views

Surface Tension of Water and Breaking through that surface tension

I know that the high surface tension of water makes it relatively more difficult for light objects to break through the surface (i.e. it's why insects can "walk" on water). So that seems to work when ...
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1answer
40 views

Are phase transitions reversible when performed at supercooled temperatures?

For the state transition of supercooled water to ice, is the process reversible? I wonder this because I want to know if I can use entropy change of the universe is 0. If it isn't reversible, how do ...
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1answer
47 views

Creating a 10 ppb Lead Nitrate Solution

I’m trying to make a 10 ppb Lead Nitrate solution as part of a concentration calibration step for a Beer Lambert’s Law experiment. I plan on performing a dilution in three steps. The calculations have ...
2
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1answer
160 views

Confusion about Titration Formula [closed]

When performing a titration of a monoprotic acid and a monoprotic base, water can not be added to the titrant but water can be added to the analyte. To prove this statement to myself, I decided to ...
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0answers
13 views

What is the order of stability for Water(H2O)/ Heavy-water(D2O)/ Semi-heavy Water(HDO) and why? [closed]

I am solving a rxn of Carboxylic Acid and Alcohol in presence of D+ instead of H+.I got stuck at the step of removal of water molecule. I think that the stable thing will be formed.But I don't know ...
3
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0answers
38 views

Thermodynamic model of inclusion process of alpha-cyclodextrin

I have a question about thermodynamic model of inclusion process of CD, published by Tabushi (DOI: 10.1021/ja00471a043). Here, in 3rd step, action is described as: "An apolar solute (guest molecule) ...
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1answer
154 views

NaCl water electrolysis without membrane, how measure the free chlorine concentration?

I'm trying to made electrolysis using water and NaCl. I need at the end a concentration of 2 g/l. How can I measure the free/active chlorine? Do you know a way to "measure" the chlorine during the ...
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1answer
48 views

How to store small amounts of gas

I need to store small amounts of gas. I already saw devices that look similar to the image below, but I don't know how they are called. Does someone here know how these devices are called? I am also ...
6
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0answers
232 views

Conductivity measurements of demineralized water - Unexpected results. Looking for explanation

I'm trying to measure the conductivity change of demineralized water over a few days. But I get results I can't explain. Setup This is the circuit and cell I'm using: Where $R_x$ is the ...
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1answer
3k views

What is the electrical conductivity of pool water?

What is the electrical conductivity of pool water? I tried to find some information, unfortunately without success. I need to know it to make an underwater electronic project.
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1answer
22k views

Salt concentration and electrical permittivity of water

We know that the electric flux density $D$ can be related to electric field intensity $E$ as $$D = \epsilon(\omega) E$$ where $$\epsilon(\omega) = \epsilon_0 \epsilon_r(\omega)$$ and $\epsilon_0$ ...
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0answers
23 views

Normal Mode Analysis of proteins

I'm trying to do Normal Mode Analysis for my MD trajectory. I'm following Amber tutorial (http://ambermd.org/tutorials/advanced/tutorial3/py_script/section5.htm) which uses an example of estrogen ...
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0answers
40 views

The measurement of bond angles? [duplicate]

How does one experimentally determine the bond angles of various molecules? (eg. water 104.5*)
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2answers
2k views

Can dissolving be a chemical change?

My textbook says that $\ce{SO2}$ dissolving in water produces sulfurous acid, but that seems to be a chemical change. But $\ce{NaCl}$ dissolving in water is not a chemical change. Please explain.
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1answer
92 views

Did I accidentally create phosgene gas [closed]

I accidentally mixed bleach and acetone trying to remove hair dye stains from my shower wall. The mixture turned orange when the bleach and acetone touched. Could I have created phosgene gas ...
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1answer
28 views

Why is distilled water such a poor conductor of electricity?

Water is composed of hydronium ions and hydroxide ions. Since ions do conduct electricity, why is distilled water such a poor conductor of electricity?
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1answer
102 views

How to calculate bicarbonate and carbonate from total alkalinity [closed]

It's been a long time since I did my chemistry classes and I'm currently trying to analyze groundwater samples for hydrogeology purposes. I would like to evaluate carbonate and bicarbonate ...
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2answers
209 views

Frequency of Mpemba Effect [closed]

What are the chances of warm water freezing faster than cold water? (How many percent?) Does it have to do with container size or something in it?
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2answers
2k views

What can cause artesian well water to smell?

Recently, our water from the artesian well started to smell (again). It only smells bad for only few seconds than the smell disappear. We have sulfur-iron removal system, water softener, UV lamp. ...
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5answers
156 views

Why is the molecular structure of water bent?

Water has the formula $\ce{H2O}$ and we can draw a Lewis structure with two lone pairs on the central oxygen. As a physics student and not a chemist, I think to myself, "Okay, there are two lone pairs,...
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3answers
9k views

Why is ice less dense than water?

I know the traditional explanation, which says that ice has large spaces between $\ce{H2O}$ molecules because hydrogen-bonding gives it an open structure. But what does the open structure have to do ...
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2answers
60 views

Can Na2CO3 remove temporary hardness of water?

This was asked in my test and I remembered that all compounds that can remove permanent hardness of water can remove temporary hardness of water also. But my teacher marked it wrong and I cannot find ...
2
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0answers
46 views

Total Dissolved Solids and Alkalinity [closed]

I need to calculate total dissolved solids (TDS) of various groundwater samples from chemical analyzes. I have concentrations of ions/molecules in mg/L. I’ve found various formulas to calculate TDS ...
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0answers
19 views

Protons and osmotic potential

In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
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1answer
334 views

When and how in anaerobic digestion is water dissociated?

Anaerobic digestion and methanisation of organic feedstocks is a complex series of processes that result in biogas. One way to look at this is a very top-down, stochiometric approach as in the Buswell ...
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1answer
12 views

Creating 1L of 1000 ppb stock solution of Pb2+

I’m testing on samples that require a concentration of 1000 ppb (or 1 mg/L) of Pb 2+. My first thought was to simply dissolve 1 mg of Lead nitrate in 1 L of deionized distilled water to create 1 L of ...
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1answer
15 views

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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0answers
47 views

can a vapour denser than air evaporate in a closed chamber? [closed]

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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3answers
659 views

Configuration of a water molecule?

Water molecules are described as an oxygen atom covalently (ignoring for the monent protonization/deprotonization) bonded to two hydrogen atoms with an angle of ~104° between the hydrogen atoms (like ...
2
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3answers
81 views

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
65 views

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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2answers
66 views

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 ...
5
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1answer
938 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 ...
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2answers
24 views

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 ...
5
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4answers
6k views

How is seawater alkaline?

If when water and carbon dioxide react they form carbonic acid, carbonate, and bicarbonate, how does seawater still have a pH of around 8? Doesn't a compound need an hydroxide ion to be a base?
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1answer
38 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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0answers
68 views

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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