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.

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770 views

Dissolution of Lithium in Methanol

Easy question to kick off my chemexchange membership! I'm learning chemistry in my spare time, and fittingly for a video art project I'm doing, decided to try a simple inorganic(?) procedure to make ...
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2answers
6k views

How do I find the theoretical pH of a buffer solution after HCl and NaOH were added, separately?

This question is about the theoretical pH of a buffer solution. Calculate the theoretical pH values expected for a $\pu{200mL}$ buffer solution containing a 1:1 ratio of acetic acid and sodium ...
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0answers
470 views

What result should I have obtained in these tests? Also, what went wrong? [closed]

As part of a Chemistry practical, I had to five different tests for things, and note down the result. Unfortunately, at least several results were incorrect, and despite hours of research, I cannot ...
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1answer
319 views

Would ionic compounds dissolve in methanol?

Question: Determine whether liquid hexane ($\ce{C6H14}$) or liquid methanol ($\ce{CH3OH}$) is the more appropriate solvent for the substances grease ($\ce{C20H42}$) and potassium iodide ($\ce{KI}$)....
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0answers
242 views

What's the density of a frozen ethanol or ethanol solutions?

How can we know what's the density of ice (water), but there's no data on how much is the density of frozen ethanol? (as far as I know)
7
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2answers
344 views

Apparent contradiction in the type of deviation of an ethanol-water mixture

For a mixture of $\ce{EtOH}$ and $\ce{H2O}$: $\Delta H_{\text{mix}} < 0$ (exothermic) and $\Delta V_{\text{mix}} < 0$ (volume contraction). This means that the unlike interactions are stronger ...
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0answers
229 views

How does the molarity of a solution change on boiling off the solvent?

The dilution equation $$M_1V_2=M_2V_2$$ is an equation that can be used to calculate how adding water can impact the volume and molarity of a solution. So I was wondering if this equation would apply ...
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1answer
287 views

What is the stability of Pregnenolone in various mediums? [closed]

I have some pregnenolone powder that I want to dissolve it in to a liquid medium for later human ingestion, some potential medium choices would be: alcohol, fruit juice, water, olive oil. I am trying ...
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1answer
613 views

Chemical potential of mixtures of ideal gases and the Gibbs-Duhem equation

As is well known for a constant composition system, $\mu$ (symbolizing chemical potential) is equal to the molar Gibbs energy. Using $$ \mathrm{d}G = V\mathrm{d}p-S\mathrm{d}T, $$ we can write $$ \mu =...
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2answers
101 views

Crystallisation problem

I have an aqueous solution of N,N-dimethylphenylalanine methyl ester hydrochloride and I need to crystallise it as a salt. I'm afraid of increasing the temperature or the concentration of acid due to ...
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3answers
663 views

How to make a pH 6.8 Tris buffer?

To preface this, I am a biologist. I need to make a $\mathrm{pH}=6.8$, $\pu{1 M}$ Tris buffer. We have access to Tris base and Tris Hydrochloride. (Unfortunately, none of the fancy Tris compounds ...
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3answers
722 views

Saturated vs Supersaturated

The way I was told is that a saturated solution contains the maximum amount of solute and a supersaturated solution contains more solute than a solution can hold at a particular temperature. But I was ...
3
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1answer
114 views

Flaw in my logic on Henry's Law?

It states mathematically $ p=Kx $ where $x$ is mole fraction of dissolved gas and $p$ is partial pressure of the gas. Dissolution of gases is exothermic, so with increase in temperature, solubility $x$...
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0answers
34 views

QM modelling of charge separation reactions

I have a general question regarding the modelling of reactions in which neutral reactants form charged species/ions (in solution). How can one get the energetics approximately right on reactions like ...
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0answers
50 views

Can the solutions for the Briggs Rauscher experiment be made ahead of time and stored?

I will be performing the Briggs Rauscher Oscillating reaction as a part of an investigation into the effect of heat on the antioxidants. This will require 3 solutions to be mixed together, as shown ...
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1answer
166 views

Ethanol in gasoline — will it evaporate?

If gasoline with 10% ethanol is stored for a few weeks, will the ethanol evaporate? I have read that to check for ethanol in gas is to add a little water to a container; mark the level and add gas. ...
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2answers
2k views

Why does acetic acid (CH3COOH) conduct electricity the worst in comparison to HBr, HCOONa and NaNO3 [closed]

Which of the given substances (in an aqueous solution) conducts electricity the worst: $\ce{CH3COOH}$, $\ce{HBr}$, $\ce{HCOONa}$ and $\ce{NaNO3}$? I've found this assingment included in the 2017 ...
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1answer
1k views

When can a Secondary standard solution be used for standardising something instead of a Primary?

I am writing an assignment on 'Preparing and Using Standard solutions for Use in Analysis in Titrations and Spectroscopy' and one part is asking about primary and secondary standard solutions. I ...
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1answer
1k views

Is it advisable to make vinegar at home using acetic acid?

I've taken only a couple university chemistry courses. In the lab, when we always used acetic acid in powdered form, it struck me how when buying vinegar in a bottle from the store, you must be paying ...
2
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0answers
5k views

Why is osmotic pressure the best colligative property? [closed]

The osmotic pressure method has the advantage over other methods as pressure measurement is around the room temperature and the molarity of the solution is used instead of molality. As compared ...
4
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1answer
82 views

Solubility of oxygen in liquid hydrogen; is anything near 1:2 (molar ratio) possible?

In a question on another Stack Exchange site a proposal was forwarded to premix oxygen and hydrogen in the stoichiometric molar ratio of 1:2 to be used as rocket fuel, as opposed to the standard ...
2
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1answer
121 views

Is volume expansion possible upon dissolution of solute?

I am aware that there is volume reduction upon dissolution of ionic solutes, due to the formation of hydrated spheres of aqueous ions where water molecules aggregate around the solute ions. But ...
2
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2answers
95 views

how to display diffusion to a young audience?

I need to display some science topic pertaining to the atomic bombs, or atomic history in some way to children of approximately middle school level. So I've decided that something interesting to cover ...
4
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1answer
173 views

Why is Iron very rare in seawater compared to many other elements?

I don't know the associated technical words to research this question. There was high presence of Iron in the oceans in anoxic precambrian times, and today copper is 5 times more abundant in the ...
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1answer
39 views

Dilution calculations

$\pu{5 mL}$ of $\pu{0.012 M}\,\ce{Pb(NO3)2}$ is mixed with $\pu{5 mL}$ of $\pu{0.030 M}\,\ce{KI}$. $\ce{PbI2}$ forms. Calculate the diluted concentrations of $\ce{Pb^{2+}}$ and $\ce{I-}$ ions. I ...
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3answers
1k views

Calculating the density of a saturated salt solution

Is there a way to calculate the density of a saturated salt solution from the solubility limits or does it have to be experimentally determined? First instinct, is to add the mass of the salt to ...
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3answers
2k views

How much calcium hydroxide will precipitate after addition of sodium hydroxide into saturated calcium hydroxide solution?

Below was question 34 in the USNCO 2017 exam: If $\pu{0.10 mol}$ of solid $\ce{NaOH}$ is added to $\pu{1.00 L}$ of a saturated solution of $\ce{Ca(OH)2}$ $(K_\mathrm{sp} = \pu{8.0 \times 10^-6})$, ...
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1answer
710 views

What is the logic behind the division into groups of anions and cations in qualitative inorganic analysis? [closed]

I find it very confusing and hard to memorize. Is there a way to deduce it, like understanding how it is derived, or is it just one of a lot of ways you can do it but is the standard one? Do people ...
2
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1answer
354 views

USNCO Question - Determining solute using spectrophotometer

Below is a question from the 2017 USNCO: The concentration of which approximately 0.01M solution could be most accurately determined by a visible spectrophotometer (or colorimeter)? (A) $\ce{Mn(NO3)...
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2answers
472 views

Is HDPE affected by long term exposure to methanol?

For at least several years I'be been storing various chloride solutions with methanol as a solute in Nalgene containers, which I believe are made from high density polyethylene (HDP). But recently ...
4
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2answers
669 views

How to determine if two calibration curves are parallel, within 5%

I have complex matrices and I need to make sure the matrix does not affect the measurement of my analyte. To do that, I need to prepare samples of my analyte in a solvent and of the matrix reinforced ...
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1answer
57 views

Chemistry of making glass [closed]

To boil glass, the lime and sand mixture of potash was heated and the off gas spent $\pu{125 mL}$ of barley hydroxide solution (density $\pu{1.14 g mL-1}$). The mass of the sediment was $\pu{4.925 g}$....
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1answer
801 views

Why does solvent particles move towards solution when semi permeable membrane is added?

When a SPM is added in between solute and solution the water molecules move towards salt water even though the concentration is same both sides. Why does this happen? According to SPM's perspective, ...
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0answers
76 views

Kinetics of A + 2 B -> C reaction

A reaction $\ce{A + 2 B -> C}$ is carried out in constant volume at $\pu{227 ^\circ C}$. the volume is $\pu{2 L}$. There is no $\ce{C}$ at the beginning. $[\ce{A}]_0 = \pu{0.035 mol L-1}$. $\ce{B}$ ...
0
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1answer
4k views

pH value of a buffer solution of HClO and NaClO [closed]

So, I have 200mL of HClO 0,64M. I mix it with 0,1mol of NaClO. How should I calculate the pH? My question is about this: should I keep attention about changes made to the solution volume after adding ...
8
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1answer
2k views

Why does Dead Sea water feel greasy?

The best explanation I found so far is this: These salts (magnesium, potassium, sodium, etc.) are responsible for the "greasy" feel of the water. But it doesn’t say which salts exactly are ...
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2answers
1k views

Converting mass percentage of a solution into its density? [closed]

Is there a way of converting mass percentage of a solution to obtain its density? (With mass percentage been given and the compounds which are mixed to form the binary solution)
5
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0answers
254 views

Why droplets of water and ethyl alcohol solution freeze weirdly? [closed]

I'm doing a project where I freeze water drops and solutions with water and ethyl alcohol. It's a phenomena where drops create a conical shape at the end of their freezing. But with ethyl drops, with ...
5
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1answer
385 views

Is there a paper glue that is NOT dissolved by acetone?

Short version of the question: I need a spray-on glue that will stick paper to wood that isn't dissolved by acetone. Long version: I am trying to glue paper on wood. It's a big sheet of paper and I ...
3
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0answers
651 views

Calculating total volume mixing NaCl and water

I'm (as a non chemist) trying to calculate the the volume of a NaCl solution. The problem is that I know the volume of water prior to mixing in NaCl, but I want to know the volume of the solution ...
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0answers
452 views

Is the crystallization process of aqueous solutions of substances such as lithium chloride endothermic?

$\ce{LiCl}$ has an enthalpy of solution of $\pu{-37.1 kJ/mol}$, so its dissolution process is exothermic. Does this mean that it's crystallization process is exothermic? I'm asking since I've looked ...
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2answers
6k views

Is sodium acetate strong or a weak electrolyte?

Since it is formed of a strong base and a weak acid it should be a strong electrolyte but a chemistry teacher said that it is a weak electrolyte.....
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1answer
4k views

Why do chloroform and benzene exhibit negative deviation from Raoult's law?

Chloroform is a polar molecule, and benzene is nonpolar. Shouldn't the chloroform-chloroform and benzene-benzene intermolecular forces be stronger than chloroform-benzene interactions (like dissolves ...
2
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0answers
298 views

What determines the maximum size of salt crystals as grown in flux growth?

Like many other children, I grew single crystal salt crystals in a salt solution. This is a common and fun experiment for children. However, with both this experiment, and with flux growth methods ...
7
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1answer
325 views

Is it possible to have Volume(solution) < Volume(solvent before adding solute)?

I understand the answer to the question "Is it possible to have Volume(solution) < Volume(solvent) + Volume(solute)?" is "yes" -- but it is possible that adding a solute causes the solvent to ...
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0answers
59 views

Why does soapy dishwater lose soapiness over time?

I wash dishes by making a concentrated solution of dishsoap (eg dawn) and water. Sometimes I'm lazy and forget to wash the container containing the soap solution, and it sits on the counter overnight....
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2answers
13k views

Why does like dissolve like?

Polar solvents love polar solutes to be dissolved in it and non polar with non polar. Often said as like dissolves like. Okay, polar loving polar can be understood with help of the facts: same polar ...
2
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1answer
113 views

Binary diagram and two phase region

I know that to find the composition in a two phase region of a binary diagram we have to draw the isotherm and to look at the intersection with phase boundaries. But why? Is there a demonstration?
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1answer
489 views

what is the final concentration of the mixture [closed]

In a bizarre twist of chemical fate, an accident results in you results in you mixing 2L of a 3.00M solution of NaCl with 4L of a 1.50M solution of NaCl. what is the final concentration of the mixture?...
2
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1answer
1k views

How do Invert Sugars deter crystallization in Sucrose solutions?

Invert Sugars, by themselves, are notorious for their reputation to crystallize fast (think honey), but their addition to solutions of Sucrose (think simple syrup) deters the crystallization process. ...

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