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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18 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 ...
4
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1answer
25 views

If volatility depends on intermolecular forces, then why in Raoult's law, two substances have different volatility?

I have a doubt, Ideal solutions are solutions where intermolecular forces between solute-solute and solvent-solvent are nearly equal to solute-solvent. Since intermolecular forces between A-A = B-B, ...
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0answers
44 views

Why is the entropy of a NaOH solution negative? [closed]

Why is the change of entropy of the solution of $\ce{NaOH}$ in water negative while that of $\ce{KOH}$ is positive? It makes sense that entropy of $\ce{KOH}$ should be positive as degree of randomness ...
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0answers
19 views

Clarification on temperature-composition phase diagrams of a Binary Mixture

After watching this video: https://www.youtube.com/watch?v=SPrybbPdVDQ, I have come to the conclusion that on a temperature-composition curve(for two components, $\mathrm{A}$ and $\mathrm{B}$), there ...
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1answer
101 views

Cheap but efficient disinfectant / biocide for home lab

EDIT I am forced to reword my question about a chemical mixing ratio. I have seen in Wikipedia that peroxide ($\ce{H2O2}$) and Acetic Acid can be mixed to Peracetic acid - this is an equilibrium. I ...
3
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2answers
631 views

Mixing of powders to make stock solutions

For a solution such as: Luria-Bertani (LB) Broth: 10 g tryptone 5 g yeast extract 10 g of NaCl ($M = 58.44\ \mathrm{g/mol}$) q.s. to 1 l, pH to 7.2, autoclave. I would like to make a bulk amount ...
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1answer
2k views

How to determine the empirical formula given mass percentages of the elements and the molecular weight?

A compound has $67.3 \% \rm~C,4.62 \%~N,6.93 \%~ H$ and O. Determine the molecular formula of the compound knowing its molar mass is $283\rm~\frac{g}{mol}$. My solution : The percentage for the ...
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3answers
90 views

Dynamic equilibrium in unsaturated solutions

One standard definition of equilibrium in beginner chemistry is that for a reversible reaction, (dynamic) equilibrium has been achieved when the rate of the forward and backward reactions are equal. ...
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1answer
437 views

Why does freezing point decrease when vapour pressure decreases in dilute solutions?

I was studying colligative properties of dilute solutions, and one of the properties was freezing point depression. The confusion I had was that, if vapour pressure decreases, it should be easier to ...
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1answer
43 views

Can compounds dissolved in different miscible solvents react?

For example, can crystal iodine dissolved in ethanol react with sodium thiosulfate dissolved in water when mixed together?
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1answer
50 views

Is it possible to prepare a 0.1 N solution of HCl and methanol? [closed]

In my lab guide I read: "Use a $\pu{0.1 N}$ solution of methanol-chloridic acid $(9:1)$ for the anthocyanin extraction", so I tried to calculate the volume of $\ce{CH3OH}$ and $\ce{HCl}$ to prepare it,...
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1answer
26 views

Can there be a compound which stops the pesticide from entering into the fruit or vegetable? [closed]

Can there be a compound which stops the pesticide from entering into the fruit or vegetable? For example, a solution which is sprayed before pesticides and somehow blocks pesticides from entering into ...
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1answer
10k views

Why do non-polar covalent compounds dissolve in non-polar covalent compounds only?

My textbook says that electrovalent and polar covalent compounds dissolve in electrovalent compounds and polar covalent compounds but not in non-polar covalent compounds. I understand the reason for ...
2
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1answer
101 views

Kohlrausch Law and conductivity

Im writing up a lab report at the minute and part of it concerns ions in solution and how they affect conductivity. I've been doing lots of reading and I think ive got the grasp of most of it, but its ...
3
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1answer
415 views

Properties of azeotropes

Consider two liquids with vapour pressures in pure form being ${P^o}_A$ and ${P^o}_B$. ${P^o}_B >{P^o}_A$ which implies liquid B is more volatile. If the liquids formed an ideal solution, then a ...
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2answers
88 views

Freezing Point Depression and Temperature Decrease

I don't have a problem understanding the chemical mechanisms underlying freezing point depression or colligative properties in general, but what I cannot seem to grasp is how if you add salt to ice ...
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2answers
6k views

Why does shampoo lather much more the second time it is applied?

When I shampoo my dirty hair, the first time it does not lather very much. The second time it lathers a lot. Why is this?
3
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1answer
2k views

Acidic and alkaline salt solutions: why do some salt form acid/bases while others don't [closed]

I have a question regarding salts and their solutions. How come some salts, like sodium carbonate and ammonium chloride, produce acids/bases when dissolved in water? Moreover, how can you predict ...
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0answers
18 views

How can I make a reference humidity environment with NaOH pellets? [duplicate]

I have NaOH pellets at my disposal. Some of the pellets are degraded, but most are not, and I can provide a new batch if needed. I would like to test several humidity sensors in an environment with a ...
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1answer
52 views

Difference of Ascorbic acid dissolved or precipitated in Glycerol?

Difference of Ascorbic acid (AA) dissolved or precipitated in Glycerol? Referring to pat US20110008445A1 Solution 1 At 25C, AA was dissolved in glycerol and alcohol (subsequently removed by ...
2
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2answers
144 views

Thickening and/or slowing evaporation of IPA-based ink

The conundrum I have a security printing ink that I make by adding an IR-absorbing dye to a 50/50 mix of Isopropyl Alcohol and distilled water. The ink solution is pale green but dries virtually ...
2
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1answer
57 views

What is the interaction between dissolved ions of opposite valence in a solution at rest?

NaCl is dissolved in water. Ions sodium and chloride are sufficiently free from each other so that they may occupy different regions of the solution after an active transport process through a ...
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2answers
215 views

Phenolphthalein Indicator mixed with base that first turns pink and then clear

What occurs in the following situation: After adding 2 drops of Phenolphthalein Indicator (an indicator that turns bases pink and stays clear for acids,) into a unknown solution, the solution turns ...
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2answers
374 views

Volume change in positive deviation from Raoult's Law

Let us take a mixture of ethanol and acetone as an example. When ethanol is mixed with acetone, the hydrogen bonding between ethanol molecules gets disturbed as actone molecules get in between the ...
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1answer
80 views

Finding original concentration w%/w%

A question from a grade 9 admission exam: When 1 kg of salt is added to a solution of salt and water, the solution becomes 33 1/3% salt by mass. When 1 kg of water is added to the new solution, the ...
4
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1answer
200 views

Why does concentration of solutions of alkali metals in liquid ammonia change the magnetic properties?

In "NCERT Chemistry for Class XI - Volume II", in chapter "s-block elements", under the topic "Chemical Properties of alkali metals", it is given: (vi) Solutions in liquid ammonia: The alkali ...
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1answer
1k views

Vapor pressure of immiscible liquids

I have read that vapour pressure of a mixture of two immiscible liquids is $$P=P^0_A + P^0_B$$ where A and B are immiscible liquids. If they are immiscible, they would form separate layers. Thus ...
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1answer
66 views

Home made dispersion/solution with detectable >0.1μm particles [closed]

Sorry for the possibly wrong terminology. I'm not a chemist and I'm not a native English speaker. Please edit the question as needed. Thank you. Is it possible to buy or prepare a dispersion with the ...
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2answers
10k views

Mixing two solutions to find overall solution

If you mix 20ml of 3m sugar solution with 30ml of a 5M sugar solution, what solution do you end up with? I did; volume = number of moles/concerntration - 3/.02 = 150 - 5/.03 = 166.6666667 - 150+166....
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1answer
33 views

Suitable safe cleaning solution for aliphatic urethane

I am looking for a suitable cleaning solution for a sprayed on coating that is an acrylic aliphatic urethane. My end goal would ideally be something that can neutralize rust, whiten and brighten the ...
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0answers
51 views

How to dissolve PLA/PCL/PMMA?

I have a research about electrospun membrane synthesis where I dissolve PLA pellets in chloroform:methanol (3:1) for 3 hours and also PCL pellets in chloroform:methanol (3:1) for 3 hours too. Another ...
7
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1answer
598 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 ...
0
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1answer
28 views

Separate less volatile component from distilling a mixture [closed]

Is it a strict rule that when we boil a mixture of two liquids, with one being less volatile than the other, the more volatile vapour has to form the greater portion of the total vapours? If it is so,...
0
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1answer
51 views

How does acetone help to make a liquid cleaner stronger? [closed]

Acetone, as a solvent, seems to behave somewhat different than other solvents. It seems to solve things other unpolar solvents do not. For example, I have two cleaner sprays from the same brand, and ...
0
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3answers
9k views

Does solute add to volume of solution?

I have to calculate the concentration of sucrose in water just by knowing their masses (and their temperature). Now, if the volume doesn't change when the sugar is being dissolved, I can do that quite ...
6
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1answer
211 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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1answer
1k views

Making artificial sweat

I'm currently working on a chemistry investigation wherein I need to dilute a compound with artificial sweat. I have looked at various forums, including this, which gave answers, but is very outdated. ...
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1answer
143 views

Why zinc sulphate solubility is higher in ethylene glycol than water?

I'm trying to find saturation point for dissolved zinc sulphate in water and ethylene glycol. Based on my knowledge, water is more polar than ethylene glycol as reflected in its higher dielectric ...
4
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2answers
102 views

Are hydroxides soluble in each other?

Let's say I have molten potassium hydroxide and then I add some Calcium hydroxide. I imagine, since there are hydroxide groups floating around, it would be energetically neutral for the calcium ions ...
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3answers
2k views

Could I settile for galvanized steel over stainless for salt corrosion resistance?

Bear with me, I'll get to the chemistry soon. I have a float tank that I want to attach a skimmer to. Unfortunately, the enclosure is weakened by cutting a hole out of the ABS plastic. The weight ...
4
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2answers
184 views

Is there a potentiometric method for monitoring salt formation in organic solvent?

I work in a pharmaceutical R+D lab, and currently aim to develop a validatable potentiometric method for determining the optimal amount of acid to add to a basified small organic molecule for ...
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1answer
35 views

Boiling point elevation and liquid solutions

$\pu{1 L}$ of an aqueous solution of urea having density $\pu{1.06 g mL-1}$ is found to have elevation in boiling point $\Delta T_\mathrm{b} = \pu{0.5 °C}.$ If the temperature of this solution is ...
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1answer
38 views

Liquid solutions and vapour pressure

"The vapour pressure of water at 80° C is 355 torr. A 100 mL vessel contained water-saturated oxygen at 80° C, the total gas pressure being 760 torr. The contents of the vessel were pumped into a 50 ...
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1answer
378 views

Equation to find specific gravity (or density) from a solution of sugar and water

Is there an equation or simple way to calculate the final density of a solution made from x grams of sugar and y liters of water? And would it work in reverse? if we have y liters of water at z ...
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9answers
437k views

Why does ice water get colder when salt is added?

It is well known that when you add salt to ice, the ice not only melts but will actually get colder. From chemistry books, I've learned that salt will lower the freezing point of water. But I’m a ...
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1answer
57 views

Change in boiling and freezing point

I recently encountered a question while solving previous year question papers for JEE. This is a JEE 2005 question. The question demands to complete this statement: Equimolar solutions in the ...
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1answer
52 views

Applying Raoult's Law in volatile solids–liquid solutions

My textbook explains applying Raoult's Law for the two cases: liquid–liquid solutions, in which the vapour pressure of the solution is due to both the components non-volatile solids–liquid solutions, ...
2
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2answers
163 views

Why doesn't the solute settle out of a solution, such as brine or sugar water? [closed]

If I have a solution of salt or sugar dissolved in water, the solute will never settle out or "fall to the bottom", no matter low long I wait. Why is that? Since salt and sugar (in their pure, solid ...
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1answer
6k views

finding cation of unknown salt in solution from precipitate

I should probably add that I was originally given an unknown solid mixture of 2 salts. I separated the insoluble salt out by centrifuging and then decanting. I found that the insoluble salt is $\ce{...
4
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1answer
76 views

Phase description for a substance dissolved in a solvent other than water?

I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for ...