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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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Converting FeCl2 to FeSO4

I have FeCl2 crystals and I want to produceFeSO4.7H2O based on the reaction below: $$\ce{FeCl2 + H2SO4 -> FeSO4 + HCl}$$ I dissolved the FeCl2 crystal in water, added equivalent amount of H2SO4 to ...
-1 votes
1 answer
37 views

chemical to prevent recrystallization of zinc and iron sulphate in solution

500 gm zinc sulphate and 280 gm iron sulphate ( total weight 780gm ) were taken in flask and water is added to make final volume 1 liter. the solution is heated to dissolve the zinc and iron sulphate ...
1 vote
0 answers
19 views

Thermoplastics crystallization during nonisothermal cooling cycles

I have tested a PAEK family polymer using differential scanning calorimetry (DSC) with heating-cooling-heating cycles under different cooling rates (heating rates remained unchanged). PAEK are semi-...
8 votes
2 answers
3k 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 ...
-2 votes
1 answer
25 views

Formation of cocrystals troubleshootin

In cocrystal formation what would the possible reason be for the precipitation of an amorphus oily precipitate not suitable for PXRD? Solvent was DMF and the reagent were L-thyroxine and ...
2 votes
0 answers
179 views

Drying sodium tetraborate for use as a standard

I am currently attempting to purify technical grade sodium tetraborate decahydrate by recrystallization for use as a titration standard. I don't have a requirement for a specific grade or purity. I'm ...
6 votes
1 answer
5k views

Are electronic descalers a scam?

It seems there are some electronic kits sold around nowadays by major retailers (e.g., Home Depot and Amazon) claimed to remove built-up scale from water pipes. But, do they actually work? If so, ...
1 vote
0 answers
79 views

Why isn't my sodium acetate demo working?

So I'm trying to do the sodium acetate tower demonstration that I've seen a ton of videos on. I don't have sodium acetate and I am making it from a liter of 5% distilled white vinegar and pure baking ...
3 votes
1 answer
2k views

Growing crystals that are in a magnetic field or subjected to an electric field

I know different crystals resonant at different frequencies but is it possible to grow crystal at a certain frequency. An example would be growing crystals using Epsom salt or Alum in a magnetic ...
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0 answers
127 views

Can cooling rate affect the yield of crystals?

Cooling an acetanilide mixture with an ice bath has resulted to a heavier amount of acetanilide crystals than cooling the container slowly (setting it aside in the lab). I have gotten different ...
-2 votes
2 answers
453 views

What is the difference between alloying and doping? [closed]

When compared to doping, how is alloying different? What modifications to the structure are brought about by both of these?
13 votes
1 answer
8k views

How to make pyramid-shaped NaCl salt crystals

I'm attempting to make sea salt pyramids like the one below. I understand this needs to be evaporated at a reasonable speed to stop the crystals forming a cube, as the when formed quickly, the edges ...
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1 answer
1k views

Steps of crystallization

An excess of copper(II) oxide is added to dilute sulfuric acid to make crystals of hydrated copper(II) sulfate. The processes listed may be used to obtain crystals of hydrated copper(II) sulfate. ...
1 vote
1 answer
74 views

Slow evaporation versus vacuum evaporation

I have a salt in water and I want to evaporate the water. I'm wondering, what will be differences (if any) in the character of the crystals in a few scenarios: Slow evaporation - let the solution sit ...
1 vote
0 answers
25 views

Which ionic radius is most relevant for anticipating co-crystalization?

In the context of anticipating the likeliness that elemental impurities co-crystalize into the crystals containing an element of similar radius (see this question), which is the relevant radii to ...
0 votes
1 answer
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What are good ways to anticipate co-crystalization of different metal ions?

What rationale (purely theoretical/assumptive, or known by experience / backed by evidence) would you use in an attempt to effectively anticipate which other metal or elemental ions are most likely to ...
6 votes
1 answer
458 views

Can uranium be used to color aluminium oxide based gemstones, and/or diamonds?

Re-hosting this question from Physics to Chemistry, lightly edited. Rubies and sapphires are chemically equivalent to the mineral corundum, with the exception of transition metal impurities that ...
3 votes
1 answer
4k 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 ...
-1 votes
2 answers
172 views

Recovery of Urea from aqueous solution [closed]

When adding Urea to water, the reaction is highly endothermic. I was playing with the idea of using that for a Desktop cooling system, but for that, I'd of course have to recover that Urea from the ...
7 votes
5 answers
3k views

How can I roughly measure a fraction of a gram?

My son got a crystal making kit (from a relative) and it lists seed crystal weights of 0.5g for a small crystal solution and 0.75 g for a large crystal solution. The trouble is I (his father) don't ...
0 votes
1 answer
205 views

How do I crystallize Sodium Acetate w/o a crystal? [duplicate]

I made some sodium acetate. Definitely not pure or anything close. But I just did it as a quick experiment. Just some vinegar and baking powder. When I search how to make $\ce{NaOAc}$ crystals, people ...
11 votes
3 answers
817 views

Why is it so difficult to crystallise anything in a glass capillary?

I'm talking about very fine glass capillaries with a diameter under 1 mm. I've found that if I carry out melting point analysis, the material in the capillary doesn't crystallise again. I did wonder ...
2 votes
1 answer
415 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 $x$...
2 votes
1 answer
10k views

Tips for maximizing yield, purity and crystal size during recrystallization

I have already asked a similar question on titrations before. In a few months, I have a test on chemical synthesis. It is marked on the percentage yield, purity and crystal size of the product. I do ...
6 votes
1 answer
713 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? ...
6 votes
3 answers
1k views

Why is sea salt coarse?

What makes sea salt coarser than other salt? I have tried checking online but no one seems to discuss this. It seems that the grain of sea salt is larger, but I don't understand since the salt is ...
-3 votes
1 answer
922 views

Best solvent for recrystallization of acetanilide? [closed]

How would you recrystallize acetanilide using ethanol and hexanes? I know this compound is not soluble with the hexanes solvent. But, where would I include ethanol in the procedure? Would I heat up ...
1 vote
1 answer
204 views

Will these K-alum crystals combine into a "cohesive/well-glued" mass?

The attempt to make a single solid mass of K-alum, using over 125 grams of McCormick K-alum powder, has resulted, in less than 2 hours, in: So besides the growth around the loop of the seed "...
14 votes
1 answer
518 views

What factors promote honey's crystallisation?

Honey is a complex mixture containing, probably, more than hundred compounds. I understand that the % of those components will affect the crystallisation. However, I am wondering what factors may ...
3 votes
2 answers
8k views

Recrystallization and purification techniques for getting a pure sample

Could someone explain in detail as to why exactly recrystallization gives a more pure solid sample? As well as why is would be better 'technique' to allow for the crystal to form slowly? I was ...
0 votes
1 answer
393 views

How to differentiate hydrous and anhydrous compound? [closed]

For an experiment, my teacher gave me containers of hydrates and their corresponding anhydrous compounds, but I have a feeling that for one of the compounds she switched the hydrate and anhydrous ...
1 vote
2 answers
919 views

If stirring negatively affects crystal purity, why is it so?

My Intellectual Expectations Intuitively, I would expect strong stirring to improve crystal purity during the process of crystalization. My rationale is that strong stirring would increase contact ...
4 votes
1 answer
231 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 votes
2 answers
2k views

How does a shock, such as the snap of the disk in a reusable hand warmer, trigger the re-crystalization of a supersaturated solution?

Reusable handwarmers are made of something dissolved nearly to its saturation point in hot water (Sodium Acetate in the case of HotSnapz) at a high temperature, and then cooled to a temperature at ...
2 votes
2 answers
2k views

Potassium Alum Crystals

This is a question regarding the crystallization of $\ce{KAl(SO4)2 . 12 H2O}$. I have an idea of what to do (I'll explain later in the explanation), but I would like to hear other suggestions encase ...
4 votes
3 answers
11k views

What are disadvantages of using sublimation vs. recrystallization as a method of purification?

I can only think that a small sample can be sublimed while a bigger sample size can be recrystallized. Are there more?
4 votes
2 answers
1k views

Shea Stearin Extraction by Dry Fractionation

I have been able fractionate palm oil and extract palm stearin using the following method: Melt the palm oil (over 80 °C) Keep the melted oil at 33.5 °C for 24 hours (using an immersion circulated ...
-4 votes
1 answer
258 views

Potassium tetraoxalate preparation [closed]

How is potassium tetraoxalate produced industrially? In fact How I can limit the reaction of $\ce{H2C2O4}$ and $\ce{KOH}$? Or is there any other route for this purpose?
4 votes
0 answers
470 views

How can should one separate and purify benzophenone from salicylic acid?

I am working with two solids and I know that they are benzophenone (s)(ketone) and salicylic acid (s) (carboxylic acid). I am curious to know what is/are the best method of extraction and ...
1 vote
1 answer
493 views

How can I purify Ferric or Ferrous acetate with a very basic lab?

I’ve been trying to make Ferric acetate by mixing vinegar with steel wool and allowing it to react. The result is successful in dying leather or wood black and acting as a mordant. Theoretically there ...
7 votes
1 answer
1k views

What is this copper compound I made?

I started with copper (II) sulfate solution left over from a recrystallization. I added sodium carbonate (definitely an excess) and about 200 of water and got a lot of bubbling. I heated it, for no ...
-1 votes
2 answers
2k views

What happens if the filter paper in vacuum filtration is BIGGER than the buchner funnel diameter? [closed]

I’m wondering what would happen if the filter paper in a vacuum filtration process is bigger than the buchner funnel diameter? I mean would some differences occurs? Or would the whole experiment ...
1 vote
0 answers
76 views

Why are colloidal dispersions stable? [closed]

Smaller particles in a colloidal dispersion are less stable than larger ones due to their higher surface to volume ratio. Therefore Ostwald ripening occurs, a process which promotes growth of larger ...
1 vote
0 answers
56 views

Anhydrous Chromium Alum production

I recently started a small project of making home-made chromium alum crystals, as can be found on many sites, videos and recipes all around the internet. I tried calculating the amount of salt I ...
0 votes
0 answers
120 views

Why does cobalt(II) chloride (CoCl2) crystal melts?

I made $\ce{CoCl2}$ crystals by making a concentrated solution. After the crystals formed I took them out of the solution for drying. After a time I noticed that they were still wet so I dried off ...
3 votes
1 answer
35k views

Why is the solid product washed with ice-cold solvent during in the last stages of recrystallisation?

Why is the solid product washed with ice-cold solvent during in the last stages of recrystallisation? Is this to remove soluble impurities? (for example) Well, what if the impurities were also ...
-3 votes
1 answer
853 views

Lead nitrate and sodium iodide [closed]

As we know that if you mix lead nitrate and sodium iodide solutions together, a yellow precipitate forms. Can you maybe add nitrate in water that may or may not have lead in it and then mix it with a ...
2 votes
0 answers
389 views

Could you form quartz crystals by melting and cooling sand very slowly?

Since glass is amorphous quartz and when you slow the cooling of something enough it will crystallize, couldn’t you melt $\ce{SiO2}$ (sand) and then very slowly cool it to cause spontaneous nucleation ...
31 votes
2 answers
5k views

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. ...
7 votes
2 answers
5k views

Recrystallisation of dibenzylideneacetone

Recently, I carried out the synthesis of dibenzylideneacetone. I had a lot of problems with the purification process, especially the part involving recrystallisation. I was instructed to carry out the ...