Sciencemadness Discussion Board - Beginner in crystal growth

Beginner in crystal growth

Alquimia - 10-10-2017 at 06:10

Hi, I'm new to the world of crystal growth.
I want to make more or less regular crystals, with cubic, tetrahedral, rhombohedral, rhombidodecahedric and octahedral forms.

I would like to know which materials are the easiest to crystallize (the fastest in terms of growth and easier to obtain locally or make), and in which liquids (again, the easiest to obtain locally or made from household materials).

So I plan to make cubic crystals of salt and maybe copper sulfate as well.
I would like to manufacture octahedral crystals similar to those of chromium aluminate or chromium sulfate, however with a material easier to obtain commercially (say, in the "store next to the house") or with some material that I can synthesize at home.

What materials do you recommend?

[Edited on 10-10-2017 by Alquimia]

[Edited on 10-10-2017 by Alquimia]

NEMO-Chemistry - 10-10-2017 at 06:20

This might help you
https://www.thoughtco.com/how-to-grow-great-crystals-602157

You mention salt so i assume Sodium Chloride, this is obviously a good start point, cheap and easy. Copper sulphate crystals are kind of mandatory for any crystal grower

. Alum would also be pretty close to mandatory

NEMO-Chemistry - 10-10-2017 at 06:21

*I forgot to mention sugar! (Sucrose) again cheap and easy

Alquimia - 10-10-2017 at 06:53

Fast question:
Can sodium aluminate replace to classical alum used in crystal growth? Will it have a similar crystal structure or shape?

This is the only substance (similar to alum) that I can obtain/manufacture at home.

DraconicAcid - 10-10-2017 at 07:00

No- sodium aluminate is nothing like alum. But if you neutralize it with sulphuric acid, you'll have sodium aluminum sulphate, which is pretty close.

Alquimia - 10-10-2017 at 07:02

Another fast question:

Commercial table salt possesses impurities of dust or something like powder or flour (which is added so that the grains of salt do not stick with moisture).

How does this product affect the final quality of the salt crystal? How can I remove this product from salt?

NEMO-Chemistry - 10-10-2017 at 07:05

Quote: Originally posted by Alquimia

Another fast question:

Commercial table salt possesses impurities of dust or something like powder or flour (which is added so that the grains of salt do not stick with moisture).

How does this product affect the final quality of the salt crystal? How can I remove this product from salt?

Ahha the technique to purify is called............. recrystallization

So take a guess what that is

.

In other words make a saturated solution and crystalize, repeat if needed, if you search this board there is a ton of info on this. But in a nutshell every time you recrystalize the product gets purer.

Would be a excellent start point.

Alquimia - 10-10-2017 at 07:08

Is there some alternative to alum easy of obtain with household materials?

NEMO-Chemistry - 10-10-2017 at 07:14

Quote: Originally posted by Alquimia

Is there some alternative to alum easy of obtain with household materials?

Define similar.....

Do you mean the shape of crystal or what exactly? I ask because DA gave you a similar one, i am assuming you ant a imialr crystal shape, is this correct?

Alquimia - 10-10-2017 at 07:18

Quote: Originally posted by NEMO-Chemistry

Quote: Originally posted by Alquimia

Is there some alternative to alum easy of obtain with household materials?

Define similar.....

Do you mean the shape of crystal or what exactly? I ask because DA gave you a similar one, i am assuming you ant a imialr crystal shape, is this correct?

Yes.

18thTimeLucky - 10-10-2017 at 07:41

You can pretty much grow crystals of absolutely everything as long as you have a solvent the chemical is at least partially soluble in or you can reach the temperature needed to melt the chemical.
Bismuth is the iconic metal of choice for metal crystal growing due to its bizarre crystal shape (google it) and the beautiful rainbow colour due to bismuth oxides that form in air, along with a relatively low melting point that should be achievable on a gas cooker/stove (just below 300^oC off the top of my head). It isn't the cheapest but you can easily purchase it on eBay or Amazon and you should be able to find plenty of YouTube videos on growing them as it is sort of done to death.
I also assume by salt you mean sodium chloride, so I will say they are extremely frustrating to grow properly. They prefer to not form single large crystals so you will need a lot of patience. I suggest growing copper sulfate crystals first as they are by far the easiest, prettiest, cheapest etc etc.

A few chemicals I would recommend would be potassium chloride, sulfur and iron sulfate.
Potassium chloride I found mine as diet salt (potassium chloride instead of sodium chloride or sometimes half of each) but can also be found sometimes as a salt for water softeners. It forms pretty white needle-like crystals and you can just use water to dissolve it.
Sulfur also forms needle-like crystals except with a yellow colour. I find my sulfur as a 98% pure fertiliser. Sulfur although isn't soluble in water but is soluble in some nonpolar organic solvents such as toluene which I believe can be found in some paint thinners/removers (I think NurdRage on YouTube did a video on extracting toluene from OTC products).
Finally iron sulfate produces lovely green crystals, is soluble in water and I found mine as a 99% pure fertiliser. It is quite close to copper sulfate but iron sulfate seems to like decomposing in water and air into brown iron oxides and hydroxides (I think) so when growing crystals you should keep the solution acidifed with a little sulfuric acid and paint the crystals with clear nail varnish when you take them out.

I hope you find this useful and I didn't waffle on too long! (Crystal growing is a great hobby) Also I don't know much about alum crystals unfortunately.

NEMO-Chemistry - 10-10-2017 at 07:56

I think if he cant get alum easily then sulphur and toluene are out. I cant get toluene in the UK easily...

I found sea salt crystals really easy to grow, not sure why they should be easier than table salt though.

Copper sulphate is a must do, as i doubt any chemist alive hasnt done copper sulphate crystals

(watch 99.9% members declare they havnt ).

Sulphur is a aim of mine when i can get hold of cheap enough toluene.

NEMO-Chemistry - 10-10-2017 at 07:59

just a quick thought, are you sure you cant get alum? Cant remember what its used for, but i am pretty sure super markets sell it in the spice section, i think** its used for pickling but dont quote me on that.

on the salt purifying thing, this should do for most things...

https://www.thoughtco.com/purify-sodium-chloride-from-rock-s...

have a really good look around that site, its more info than you think if you look hard enough

[Edited on 10-10-2017 by NEMO-Chemistry]

wg48 - 10-10-2017 at 08:10

Toluene is avaiable on Ebay at about £10/l including postage cheaper if you buy several litres.

crystal grower - 10-10-2017 at 08:12

I love sulfates. Using different crystalizing temperatures and/or addition of alcohol, H2SO4 etc. you can get many diferent forms of basically the same "boring" compound.
I haven't heard of anyone who haven't crystalized CuSO4.5H20 at some point of time

. But have you ever tried the trihydrate, or even the anhydrite

?
http://chem.pieceofscience.com/?p=1485

Or let's say nickel sulfate. If you just recrystalize NiSO4 normally, you'll end up with not so appealing green crystals which dehydrate very easily.
But if you know how to make alfa form of NiSO4.6H20 you'll get something (at least IMO) extraordinary:
(Pic on the bottom)

http://chem.pieceofscience.com/?p=1336

And regarding NaCl crystals, you just need to add some FeCl3 to the solution if you want to get nice cubes

.
http://dmishin.blogspot.sk/2014/08/crystal-growing-table-sal...

I hope you'll find this useful...

Edit: @NEMO-Chemistry I've just noticed what you wrote about CuSO4. Absolutely right

.

[Edited on 10-10-2017 by crystal grower]

ninhydric1 - 10-10-2017 at 08:23

If you have access to potassium nitrate you can grow needle like crystals too.

NEMO-Chemistry - 10-10-2017 at 08:31

Quote: Originally posted by wg48

Toluene is avaiable on Ebay at about £10/l including postage cheaper if you buy several litres.

Thx I will give it a try, Ap** on ebay i have used in the past. the problem i have with them and others is I live in Scotland, while most the major couriers say they serve my area, in fact most use subcontractor couriers for where I live. This normally means i pay alot for postage.

I dont live in the Highlands (far from it), but alot of ebayers of late have really stung me on postage.

Thx for the tip though

18thTimeLucky - 10-10-2017 at 08:46

Quote: Originally posted by NEMO-Chemistry

I think if he cant get alum easily then sulphur and toluene are out. I cant get toluene in the UK easily...

I found sea salt crystals really easy to grow, not sure why they should be easier than table salt though.

Copper sulphate is a must do, as i doubt any chemist alive hasnt done copper sulphate crystals

(watch 99.9% members declare they havnt ).

Sulphur is a aim of mine when i can get hold of cheap enough toluene.

You are probably right as I looked up the NurdRage video and he extracts the toluene by distillation which if Alquimia is new to crystal growing then I doubt they will have distillation apparatus and I shouldn't have mentioned that. Although saying that, wg48 is right, I haven't ever bought toluene off eBay but it seems easily avaliable to people in the UK like both of us. I'm not sure why I didn't mention this is my post, I must have forgot you could.
EDIT: I was about to post this but realised you have acknowledged what wg48 has said but I'll leave this how it is.
Also I have heard from others sodium chloride crystals are a pain to grow although I haven't actually gone past growing a bigger crystal from a seed crystal. I grew some seed crystals but you can see why I didn't want to continue after a few days by these pictures. Maybe I will return to this project though.

NEMO-Chemistry - 10-10-2017 at 10:50

I am going to try salt again, i used sea salt last time, maybe it had some impurity that made it work ok. I will try table salt and the stuff i used last time.

interesting that ferric chloride helps, looking at your pics that is way different to how mine behaved, but your pics tally with much of what google says. So looks like i got lucky with my salt and it isnt as easy as it turned out to be for me.

LearnedAmateur - 10-10-2017 at 12:03

Both caffeine and benzoic acid have similar interesting behaviour during crystallisation, because of their dramatic increase in solubility (water) when heated. Letting the hot solution cool will create a massive supersaturation at room temperature and merely scratching something against the side of the container will cause a 'snowstorm' of small, needle like crystals within minutes which is pretty mesmerising to watch. Respectively, 50g and 20g per 100mL should dissolve well in ~80C water and this is left to cool completely undisturbed in the open air.

Alquimia - 12-10-2017 at 00:48

How I can decrease the NaCl solubility of salty water?

NEMO-Chemistry - 12-10-2017 at 02:59

Quote: Originally posted by Alquimia

How I can decrease the NaCl solubility of salty water?

I think you mean how do you get crystals to form?

If I have what you mean correct.......

Once you saturate the solution, boil it so it evaporates. Boil say 1/3rd away and let it cool, if you stick it in a fridge then even more form.

This is how to get the small seed crystals. When you want to grow larger ones then you use a saturated solution, but you let it evaporate much more slowly.

Filter it every few days to get any crystal that have formed on the sides or bottom out, in an ideal world the only crystal you want in a crystal growing solution is your crystal.

Try and cover the container to stop dust and stuff getting in, I use tights (stockings), over the top and some cotton wool on top of that. Dont seal it with something that will stop evaporation.

You need to read that sight i linked too, most this info is in there. Not that i mind answering, but it may get you answers quicker.

If i misunderstood your question on less salty water then sorry. The way its asked is likely to get an answer like add more water.

But i think your asking how to get the crystals.

Also as a general rule, when you super saturate a solution you do it with a warm solution, normally below the boiling point. But i have seen advice thats counter to this.

Alquimia - 12-10-2017 at 03:59

I mean accelerate precipitation by losing the solubility of the salt in the water, using some more chemical additive (another salt or liquid).

I have clear the whole process, the supersaturation of very hot water and then cooling fast, but for sodium chloride is not enough.
The solubility of this actually changes insignificantly with temperature.

[Edited on 12-10-2017 by Alquimia]

LearnedAmateur - 12-10-2017 at 04:12

Other than decreasing temperature, adding a miscible liquid will produce the same effect provided that your solute is less soluble in it. Try adding some ethanol or methanol - the latter can dissolve 15 grams of NaCl per litre whereas the same volume of water will hold around 359 grams, at room temperature. This will only work for solutions that aren't saturated though, since you'll just end up salting out your solvent and this is easier the more hydrophobic you get (so isopropyl alcohol for instance will probably be fairly useless here).

MrHomeScientist - 12-10-2017 at 06:48

Mixing in an antisolvent will just cause the dissolved salt to crash out, leaving you with a fine powder. There is something called the "common ion effect" that reduces solubility - if you have a lot of chloride ions already in solution, sodium chloride won't dissolve as well. I found this out firsthand when neutralizing concentrated hydrochloric acid with sodium hydroxide; the NaCl formed fell out of solution instead of dissolving!

But any effort made to reduce solubility is going to run counter to your goal of making nice large crystals. The key to large single crystals is time; there's no getting around that. The slower you allow them to form, the larger they will become. Either allow a saturated solution at room temperature to evaporate over weeks/months, or make a saturated solution at the boiling point and place it in an insulated box (a Styrofoam cooler works well) so it cools very slowly. In the case of NaCl you're right about its solubility profile being pretty flat, so the "hot" method is out.

I was able to grow some nice NaCl cubes from seawater. I scooped up a 5 gallon bucket of water at the beach, covered it with a towel and set it on my back porch for several months. When most of it had evaporated, it was filled with awesome little ~1cm square crystals.

NEMO-Chemistry - 12-10-2017 at 14:39

a kind of side thought, i used sea salt and got good crystals. The subject of anti caking agents came up earlier in the thread, so wondering if this actually did much to the crystal I did a little digging.

I found this

http://pubs.acs.org/doi/10.1021/cg201661y

Having read it, I think you are likely to have alot better luck with sea water, if you cant get that, then pet shops sell salt as a aquarium tonic, this contains nothing but sodium chloride, and is different to marine aquarium salt.

Its pretty cheap so might be worth a go

The more i search, the more it looks like it is down to the anti cake stuff

http://pubs.acs.org/doi/10.1021/acs.cgd.7b00023

[Edited on 12-10-2017 by NEMO-Chemistry]

Sorry but found another good resource for crystal growing for you.

http://www.uq.edu.au/_School_Science_Lessons/topic09.html

And while not the best looking crystals, i thought of citric acid as another cheap one you can do. I havnt done this one myself, but I do have citric acid so have a solution cooling as we speak!!

[Edited on 12-10-2017 by NEMO-Chemistry]

Also not sure what country your in, but i checked and Alum is indeed used widely as pickling spice, apparently its very common in shops with a spice section. So maybe check your local supermarket.

You might get lucky and get it fairly cheap, find some brand names for your country and look on Amazon for pickling spice. Where abouts are you anyway?

[Edited on 12-10-2017 by NEMO-Chemistry]