Questions tagged [solutions]
This tag should be applied to questions dealing with solutions of any kind. A solution is a liquid or solid phase containing more than one substance where, for convenience, one (or more) substance(s) called the solvent is treated differently from the other substances, which are called solutes. If water is the solvent, then the more appropriate 'aqueous-solution' tag should (also) be specified.
971
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Watercolor pigment conundrum - can a change in ionic profile induce flocculation?
A client of mine has installed an ion exchange water purifier to de-harden her tap water. After that, however, she noticed that it has negatively affected her watercolor painting. From what she ...
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1
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56
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Why is solubility affected by temperature? [closed]
Why when we raise temperature generally a bigger concentration of a soluble gets dissolved in a inorganic solvent?Is there a quantum mechanical reason why this is happening?
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2
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0
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17
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DIY Turbidity Standards?
I am trying to help my high school chemistry class make their own turbidity standards to calibrate the arduino turbidimeters they are making. Last year we tried calcium carbonate as it makes a cloudy ...
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3
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0
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33
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What is the goopy substance that forms before CaCO3 precipitates?
I do a lab where we mix a solution of sodium carbonate with a solution of calcium nitrate. As expected, calcium carbonate (white solid) precipitates out. However, if the concentration is high enough, ...
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0
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23
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Technique(s) for keeping miscible liquids of similar densities from mixing
This is likely a hybrid chemistry/physics problem.
Imagine you have a tall column of water with a high dissolved mineral content (density 1.05 g/cm^3). There is a straw that extends from above the ...
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1
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1
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51
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Does decreasing pH decrease solubility of adipic acid?
I added 3 grams of adipic acid to 150ml deionized water with heating + mixing until it was completely dissolved. This was then boiled and cooled to allow crystals to form. The maximum amount of adipic ...
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1
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36
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Any way to predict what quantities of heptane and chloroform will match the density of water?
I am trying to make a solution of heptane and chloroform that matches the density of water.
Is this something which must be done experimentally as it is generally unpredictable? Does a software exist ...
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2
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0
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75
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Eutectic plot - freezing point lowering
I have a doubt about the correlation between eutectic plots and freezing point lowering.
The freezing point lowering, as well as all colligative properties, is defined in the presence of a volatile ...
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0
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1
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60
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What are the reactions between Zinc acetate dihydrate and Methoxyethanol? [closed]
I am synthesizing a sol-gel solution with Zinc acetate dihydrate + Methoxyethanol and ethanolamine as stabilizer, and I wonder what are the reactions that are taking place in the process. Could you ...
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1
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2
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143
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What is the inconsistency in calculating the differences in Na2O and NaOH in solids (v2)?
(Note that this question has been fully edited for clarity, SE help advised not to delete the question and post another).
Background:
I have a computer model in which I feed it input data from various ...
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0
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44
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How come in biuret test the copper sulfate doesn't react with the sodium hydroxide?
As I understand the color change in the biuret test is due to the formation of a complex between the peptide (with more than 2 peptide bonds) and the $\ce{Cu^2+}$ ion, from $\ce{CuSO4}$. But before ...
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1
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33
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Decarboxylation of THCA in cannabis after plant material is mixed with ethanol [closed]
When making a tincture of cannabis, an early step is decarboxylation by roasting cannabis flowers at low temperatures (such as 230F for 30 minutes). My question is, how can one decarboxylate cannabis ...
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2
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44
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Electrolysis of Solutions
So far I've only encountered formulas to solve for solutions of single molecules while learning about electrolysis, i.e. H2O or FeCl3. This generally has involved determining the resultants, ...
0
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0
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90
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Colligative properties and binary phase diagrams
I'm having troubles with colligative properties and how to relate them to binary liquid-vapour and solid-liquid phase diagrams.
First of all, in my book it is indicated that colligative properties are ...
0
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1
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30
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Is the process of volume decrease in NaOH solutions reversible during evaporation of water from the solution? [closed]
While preparing w/w 50% NaOH solution I noticed a decrease in solution volume (5-10mL) in a 2L volumetric flask, so I am wondering if there is an increase in water volume during the water evaporation ...
2
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0
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165
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Buffer solution of NaH2PO4 and Na2HPO4
We have this exercise without solutions
From a 0.2 M $\ce{NaH2PO4}$ solution and a 0.2 M $\ce{Na2HPO4}$ solution, a buffer
solution with pH = 6.8 is to be prepared. The total concentration of
$\ce{...
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3
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2
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221
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Calculate the titer of a solution
I hope this is the right place to ask. We have this exercise without solution
One litre of diluted sodium hydroxide solution (c = 0.15mol/litre) is
to be prepared in the laboratory. The titer from ...
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5
votes
1
answer
457
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Why is water present in "pure" nitric acid and RFNA and WFNA?
Various types of nitric acid have been used in rocket fuels as oxidisers (RFNA is red fuming nitric acid, WFNA is white fuming nitric acid) as they are often hypergolic with a wide variety of fuels.
...
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1
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3
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102
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Silver recovery from sodium hydroxide solution
I have washed graphic film with sodium hydroxide solution removing the silver emulsion. Is there any way to now recover the silver from solution?
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2
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73
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Are mixtures of finely ground solid fertilizer compounds stable? [closed]
If I had a combination of the following as finely ground powders, would it be relatively stable, or would they react to form other compounds?
Sodium Nitrate
Ammonium Nitrate
Calcium Nitrate
Potassium ...
1
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0
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31
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Making a reagent preparation simpler that requires pH adjustment
I have a basic question on a reagent (solution) preparation. Here are the steps that I take to prepare the reagent:
Weigh the chemical (solid form, ammonium bicarbonate) and dissolve with DW to make ...
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1
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64
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Does addition of solute affect the rate of condensation?
I know that addition of a non-volatile solute in a pure solvent effects the rate of evaporation as the number of molecules leaving the liquid bulk per unit time decreases. However when the rate of ...
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2
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3
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323
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Why are the vapor pressure of toluene and benzene different?
We learnt to apply Raoult's law for the ideal solutions. When the questions are asked, they tell that the intermolecular forces of toluene and benzene are equal. But in the same question, they provide ...
3
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1
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54
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is it possible to make crystals of multiple organic compounds that form a homogenous mass under normal conditions
I was thinking about crystals of organic compounds recently after I had to clean beeswax off a pot. it's an extremely tedious process to remove. you have to boil water in the pot and then continually ...
0
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0
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26
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Why do we cool the solution after melting it?
We conducted an experiment to analyze the molar mass of a solid by observing the freezing point depression it brought to cyclohexane. In short, the experiment procedure is as follows
the freezing ...
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0
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44
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Would a container made of sugar eventually dissolve if filled with a sugar-saturated solution of water?
Suppose you had a bottle made of sugar glass, and filled it with water that was already saturated with sugar.
I know that with a fully saturated solution of sugar in water, no additional sugar can ...
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1
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58
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Does concentrated HNO3 oxidize aluminium to form a protective oxide layer, or is the oxide layer already present so HNO3 is unable to react? [duplicate]
Sources on the internet like this one only say that aluminium does not react with concentrated or dilute $\ce{HNO3}$.
I have seen other related questions on this site but none answers my question ...
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1
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36
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Why is 10 times phosphate-buffered saline more acidic (~6.9) than 1 time phosphate-buffered saline (~7.4)? [closed]
Recently, I've been told that similar pH shift (of about 0.5 units) was observed with 20 times NPS solution as well.
In case of NPS the authors provide the following recipe for the 20 times solution:
...
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4
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4
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115
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Determining the concentration of a very small sample of sulfuric acid
How can we determine the concentration of sulfuric acid in a very small sample?
We are working on a “mechanical” process that transports a very small amount of sulfuric acid to an instrument and we ...
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3
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0
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34
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How to calculate composition of alcohol/water mixture to achieve given concentration of alcohol vapors in air for calibrating a DIY breathalyzer?
I made a breathalyzer using a MiCS-5524 gas sensor. I would like to calibrate it so it can be close to accurate. e2v technologies — MiCS Application Note 4, Using MiCS Sensors for Alcohol Detection (...
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0
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62
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Is mass of solute included in calculation of enthalpy of solution? [duplicate]
$$
\begin{array}{lrrrr}
\hline
& \ce{MgSO4} & \ce{K2SO4} & \ce{KNO3} & \ce{NH4NO3} \\
\hline
m/\pu{g} & 15 & 15 & 15 & 15 \\
M/\pu{g mol^-1} & 120.37 & 174.26 ...
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1
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1
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82
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Why did The Action Lab say that solutes that don't dissolve as well in hot water are exothermic?
Somewhat recently, The Action Lab made a video called "Why does this powder only dissolve in cold water?" , saying the powder which was calcium acetate dissolves in cold water better than in ...
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1
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287
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Why aluminum does not form ammonia complex ion?
I learned in my textbook that zinc forms more stable complex ion with NH3 than OH- because NH3 has only one lone pair and that makes repulsion between d orbital electron in zinc and lone pair electron ...
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0
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24
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When is a solution supersaturated? [duplicate]
When does a solution become supersaturated? From a little search on Google I found that, increasing the temperature of a saturated solution and adding some more solute until it starts to precipitate ...
-1
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1
answer
63
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How do I interpret the dissolution rate unit? [closed]
I have found a paper (link) that is interesting for my research project.
The dissolution rate unit in this paper is described as $\pu{mol/cm^2/s}$.
For my project I would need the dissolution speed ...
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1
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0
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26
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Can micelles form in a polar-vacuum interface?
As the formation of micelles depends on, among many factors, the difference of polarity/relative permittivity of the solvents involved with the surfactant, I'm wondering if a polar-vacuum system is ...
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0
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0
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123
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Disposal of Metal Ion Solutions After Flame Test
I just bought a flame-test spectroscopy kit to use with our small homeschool group. It includes calcium chloride, potassium chloride, strontium chloride, and lithium chloride. I also bought a bottle ...
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9
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3
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Why is there a decrease in the total volume when NaOH dissolves in water?
When a solute is added to a solvent, the volume of the solution should be equal to the sum of the individual volume of the solute and solvent (i.e total volume), right? But why is there a decrease in ...
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1
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Will the solid formed after dehydration of a disodium hydrogen phosphate + sodium hydroxide solution be hygroscopic at STP?
Given a solution consisting of disodium hydrogen phosphate + sodium hydroxide (approaching a pH of 12), will the solid formed after dehydration of the solution be hygroscopic at STP? Which salts are ...
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2
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111
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Can ions be acids or bases?
Consider a sulfate ion, its considered a weak base. Yet I thought bases and acids were compounds meaning they were always electrically neutral? Why is a sulfate ion then considered a base? And how ...
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1
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128
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Safely removing sodium hypochlorite crystals from hard-to-reach surfaces
I have a small bathing whirlpool which wasn’t used for over ten years. It is built into the ground and I cannot reach the disinfectant container to replace it with a new one. I can access the fill-...
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2
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51
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How to remember what measure of concentration to use for colligative properties
Like the title says, how do I remember what measure of concentration(molality, molarity, mole fraction) to use for various colligative properties such as increase in boiling point when a non-volatile ...
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1
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121
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How does adding oxalic acid to water change the volume of the solution?
Does $\pu{87.4 mL}$ of $\ce{H2O}$ and $\pu{12.6 g}$ of $\ce{HOOC-COOH.2H2O}$ create $\pu{100 mL}$ of a solution?
So in our practical class our teacher wanted to make $\pu{100 mL}$ $\pu{1 M}$ aqueous ...
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1
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1
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82
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Finding the density
35.6g of NaOH is dissolved in 150g of 20% NaOH solution. What is the density od the solution?
I have tried solving this problem, but I 've come across a few obstacles.
Firstly, I found the mass of ...
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5
votes
1
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218
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Why does the 1H NMR spectrum of methacryloyl chloride show two singlets instead of two doublets for vinyl protons?
Based on what I have understood, for methacryloyl chloride there is a geminal coupling of the vinyl protons since they are not chemically equivalent. Why are two singlets observed for vinyl protons ...
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1
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1
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Is vapour pressure truly a colligative property?
Colligative properties are generally defined as
A colligative property depends only on the ratio of the number of particles of solute and solvent in the solution, not the identity of the solute.
...
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0
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32
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How to measure pottery glaze leaching?
I am looking for a way to know if glazes from pottery leach chemical compound in water.
Those are usually metal ions: cobalt, manganese, chrome, etc.
The procedure would be to place hot water in the ...
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3
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456
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Why does equilibrium of ice and water only exist at 273K at normal pressure?
I am a high school student and I am a little confused in the concept of spontaneity of a reaction and how equilibrium works for a reaction, I got some confusions:
Let's take example of freezing of ...
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0
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50
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What is the necessary and sufficient condition for a mixture to be ideal?
I am trying to understand some concepts from solution thermodynamics related to ideal mixtures and fugacity. My main question is what is the necessary and sufficient condition for a mixture to be an ...
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1
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57
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pH calculation of a mixure containing 2 strong acids and a buffer mixture
Calculate the pH of a mixtureof 10 mL 0,1 M HCl ; 5 mL 0,1 M HNO3 ; 10 mL 0,2 M HAc ; 15 mL 0,4 M NaAc.
My understanding was that I have to find the [H+] by:
finding the concentration of the products ...
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