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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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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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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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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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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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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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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2answers
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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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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
39 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
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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 ...
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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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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 ...
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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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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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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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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
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
32 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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1answer
98 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
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 ...
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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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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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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
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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
47 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 ...
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1answer
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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? [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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2answers
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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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3answers
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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
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 ...
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2answers
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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
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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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1answer
59 views

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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1answer
58 views

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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2answers
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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
27 views

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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2answers
76 views

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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1answer
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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
104 views

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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2answers
58 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
69 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
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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
65 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 ...
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2answers
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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
109 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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1answer
37 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 ...
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1answer
33 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 ...

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