Questions tagged [recrystallization]

For questions related to dissolving and subsequently precipitating as substance. The purpose may be for purifying, creating polymorphs, or other reasons.

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Is honey really a supersaturated solution? Does heating to un-crystalize redissolve it or melt it?

In the SciShow video Honey: Bacteria's Worst Enemy after about 00:30 the narrator says: Honey is only about 17% water. Most, but not all of what remains is sugar. ...
4
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1answer
532 views

Why polymorphs form?

We always hear about the different arrangements of molecules that lead to the formation of polymorphs, my question here is why would a polymorph form in the first place? The material was given enough ...
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3answers
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What is the correct name for this lab technique in crystallization?

Take a glass rod and rub vigorously the wall of the flask, the substance will crystallize out of the solution. Take a fire polished stirring rod and etch (scratch) the glass of your beaker. The small ...
6
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1answer
2k views

Saturation of multiple solutes

Can a liquid which is saturated with a single solute, dissolve a different solute, or is saturation a universal thing? I ask because I’ve seen that different solutes have different points (amounts) at ...
6
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1answer
436 views

How do native sulfur crystals form?

I was visiting an elements exhibition in the Ulster Museum (Northern Ireland) and there were these native sulfur crystals on display. My question is how do sulfur crystals like these form in nature? ...
3
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1answer
115 views

Are precipitation and crystallization both analogous between Chemistry and Meteorology?

A comment under the Space SE question Is there really precipitation on Mars? Does frost count? brings up the use of the term "precipitation" in chemistry and we wonder if precipitation in ...
3
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1answer
3k views

Why do we scratch the walls of test tube in test for magnesium or calcium basic radicals?

In test for calcium ion, we add ammonium carbonate in presence of ammonium hydroxide and then white precipitate (of $\ce{CaCO3}$) is formed which is dissolved in acetic acid and then reacted with ...
2
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0answers
925 views

Why add specifically hot solvent during recrystallization procedures instead of heating it up after?

Recrystallization methods that I have seen online and in manuals involve adding a minimum amount hot solvent to the solid mixture. Is there a reason I should do this instead of adding an equivalent ...
2
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1answer
84 views

How to read mutual solubility curves of salts with a common ion?

Came across a few graphs that represent the mutual solubility of two compounds in a solvent, for e.g., solubility of $\ce{KCl}$, and $\ce{NaCl}$ in $\ce{H2O}$. On these particular graphs, I can see $x$...
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2answers
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Recrystallizing Sodium Acetate from solution

I made sodium acetate using the following reaction: $$\ce{NaHCO3 + CH3COOH ->CH3COONa + H2O + CO2}$$ The resulting solution of sodium acetate isn't pure, it has impurities. I want to crystallize ...
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3answers
27k views

What would be the most suitable solvent for a single-solvent recrystallization?

The compound in question is acetanilide, and the solvents in question are: water, ethanol, and ethyl acetate I was thinking all three would be suitable since upon experimentation, acetanilide ...