Sciencemadness Discussion Board - Tin and Zinc Chloride Synthesis

Many thanks for that advice bloggers.

The procedures i found simply said 'careful evaporation of the water', which is meaningless.

Both these syntheses are for practice with crystallisations, as i find many compounds stubborn when it comes to getting them to crystallise with the reagent concentrations i currently have on hand.

[Edited on 2-10-2015 by aga]

Carefully reduce solvent volume till liquid appears to start thickening a bit, reduce heat and simmer a bit more, you may observe bumping at this point. Allow to cool and observe: sometimes the whole mass crystallises at once. If not, chill and leave overnight. If you find no crystals in the morning, reheat simmer slowly for some more.

Hardly precise but doing it by means of weight loss is a pain.

Sulaiman - 2-10-2015 at 15:35

aga, from http://www.uptodate.com/contents/gas-and-bloating-beyond-the... :
Foods that cause gas — Several foods contain short-chain carbohydrates called FODMAPs (fermentable oligo-, di-, and monosaccharides and polyols). FODMAPs are poorly absorbed and can result in bloating and gas production (table 2). A diet that is low in FODMAPs may reduce the amount of gas you produce.

probably makes more (non)sense ?

When I was experimenting with Sn HCl and electrolysis,
dissolving part of a tin ingot in 36% HCl was slow when warm, even slower when cold.
After the electrolysis ( https://www.youtube.com/watch?v=G1sq4hnrBgM )
the tin crystals dissolved with a quick shake or stir.
I still have the SnCl2 solution from the experiment, (with some excess HCl)
so I may be copying you sometime soon.

blogfast25 - 2-10-2015 at 16:10

@Sulaiman:

What does this have to do with hydrogen generation from dissolution of metals in acids?

Sulaiman - 3-10-2015 at 02:28

my first post was an attempt at humour in response to the response of Little_Ghost_again to OP.
clearly I have a 'unique' sense of humour

my second post was to explain my first,
and add that even with 36% HCl the synthesis of Zinc Chloride using 'lumps' of Sn proceeds slowly
and in a form with much greater surface area the reaction proceeds rapidly.

since aga has Sn, HCl and SnCl solution, I posted a link to what I think is a quick/easy yet fascinating adjunct experiment.

sorry if I detracted from the thread.

ave369 - 3-10-2015 at 02:36

I don't like to dissolve metals in hydrochloric acid directly. Not fast enough. My favourite method of chloride synthesis is through nitrate (70% nitric acid is a really fast metal devourer!), then hydroxide or carbonate (precipitated with NaOH or Na2CO3), then hydrochloric acid, the base dissolves really fast.

Little_Ghost_again - 3-10-2015 at 04:20

All I was asking was you said they got more interesting (faster), I wondered if you measured the increase of the reaction as you applied heat, interesting and faster. You bang on about measuring and experimentation so i assumed you had measured how much faster the evolution of gas was for the temperature applied.
Apparently not you just did what we all do

blogfast25 - 3-10-2015 at 06:21

All I was asking was you said they got more interesting (faster), I wondered if you measured the increase of the reaction as you applied heat, interesting and faster. You bang on about measuring and experimentation so i assumed you had measured how much faster the evolution of gas was for the temperature applied.
Apparently not you just did what we all do

This outburst appears to be a sequel to another recent rant of yours, here and borne out of spite more than science.

'Banging on' about the need to measure where possible is entirely appropriate on a forum about science. We should ALL do more measuring.

And no, he didn't 'do what we all do': some of us do present actual measurements. You should be supportive of that, rather than show your petty side, as you're doing here.

As regards aga's experiment on dissolving tin and zinc in HCl, its purpose from what I understand was to prepare the hydrated chlorides of these elements, not to measure the rate of reaction. He noticed greater activity with the zinc than with then tin and concluded rightly zinc reacts faster. No measurement was needed here, simple observation sufficed. But to actually measure reaction rate would of course require, well.. some measurement or other.

So think about that for 5 seconds next time, before you shift into 'nene nenener' mode.

[Edited on 3-10-2015 by blogfast25]

blogfast25 - 3-10-2015 at 06:51

Quote: Originally posted by ave369

I don't like to dissolve metals in hydrochloric acid directly. Not fast enough.

This is such a broad statement that it's almost meaningless. The rate of dissolution of metals in HCl varies vastly, from very fast to almost zero.

[Edited on 3-10-2015 by blogfast25]

aga - 3-10-2015 at 06:52

Quote:

sorry if I detracted from the thread.

It's one of my threads Sulaiman - no danger of detracting from it !

I didn't get the joke so yours must be a very oblique sense of humour

Quote:

I don't like to dissolve metals in hydrochloric acid directly. Not fast enough.

The Nitrate route sounds interesting and this dissolution of Sn in HCl solution is painfully slow even with heating.

Strangely the ZnCl₂ has gone Ferric Chloride colour. I tested it for Fe2/3 ions, and the result was negative. Same for SO₄ ions. Will try boiling it dry.

Quote:

You bang on about measuring and experimentation

These experiments started with a spreadsheet to calculate the stoichimetry of the HCl gas needed using sodium chloride/sulphuric acid based on 25g of metal, and also to set a target yield figure.

A quick test of the Zn powder convinced me to just use the 20% HCl i have instead of HCl gas. The metal samples were weighed to 0.01g at the beginning.

Seeing how the steam and HCl boils off at an unknown rate, i decided to add more, then some more, then add an RBF for a bit of reflux, then some more HCl.

All noob errors as i have not done either of these before.

If either (or both) succeed, then i'll refine the details down to a simple process with exact quantities of reagents required.

Edit :

Post an experiment here yourelf one day LG2.36, maybe even with some calculations.

[Edited on 3-10-2015 by aga]

blogfast25 - 3-10-2015 at 06:58

Tin dissolves in nitric acid but only to yield highly insoluble SnO2. In the presence of lots of chloride ions I expect the complex ion hexachlorostannate, SnCl62- to form. Note that that's an Sn(+4) species and not Sn(2+)!

That's a drawback of using nitric acid or HCl + nitrate: it oxidises the metal to its highest oxidation number.

Concentrated solutions of ZnCl2 in strong HCl do appear yellowish.

[Edited on 3-10-2015 by blogfast25]

deltaH - 3-10-2015 at 07:36

Tin-chloride pourbaix diagram courtesy of https://theses.ncl.ac.uk/dspace/bitstream/10443/891/1/Buckle...

if anybody's interested.

Notice that the dominant species of tin will be SnCl4(2-) at low pH and E. Perhaps by using a 1:2 amount of salt and HCl on a mole basis as the etchant, the tin can be isolated as the salt Na2SnCl4. That might crystallise considerably easier than SnCl2 and should still be good for a gold test.

[Edited on 3-10-2015 by deltaH]

S.C. Wack - 3-10-2015 at 07:44

Blanchard uses nitric acid...with the HCl, and "nearly the calculated yield of stannous chloride should be obtained"...I'd go with Blanchard.

deltaH - 3-10-2015 at 07:54

Yes, the trick is not to use an excess of nitric acid. Then the tin(0) can reduce tin(IV) to tin (II), dissolving more metal in the process. You can also try bubbling oxygen through instead of using nitric acid. You would need to stop bubbling the oxygen before you dissolve all the tin, else you will end up with tin(IV), as SnCl6(2-) solution.

[Edited on 3-10-2015 by deltaH]

blogfast25 - 3-10-2015 at 08:43

Quote: Originally posted by S.C. Wack

Blanchard uses nitric acid...with the HCl, and "nearly the calculated yield of stannous chloride should be obtained"...I'd go with Blanchard.

Mixtures of HCl and HNO3 oxidise Sn(0) to Sn(IV). I've done this countless times and reported it on this forum a few times. It's an easy way to prepare (NH4

2SnCl6 or K2SnCl6.

Nitric acid alone oxidises Sn to SnO2. Personal experience and references bear that out. So do the SRPs.

Perhaps if you use a high ratio of HCl to HNO3 that might speed up dissolution and yield mainly Sn(+2). Until your HNO3 runs out, of course.

Very finely divided tin dissolves in hot strong, non-oxidising acids quite quickly. For one analysis I reduced a hexachlorostannate solution with Al strips at low pH. Fine, elemental Sn formed first, this the dissolved in the acid reserve very quickly, a matter of maybe 30 seconds, to Sn(+2).

[Edited on 3-10-2015 by blogfast25]

S.C. Wack - 3-10-2015 at 09:43

You realize there is always undissolved tin in Blanchard's preparation? More likely than not it works perfectly.

blogfast25 - 3-10-2015 at 10:01

Quote: Originally posted by S.C. Wack

You realize there is always undissolved tin in Blanchard's preparation? More likely than not it works perfectly.

Yes.

This one (similar) recommends adding a piece of Pt foil:

http://www.prepchem.com/synthesis-of-stannous-chloride/

aga - 3-10-2015 at 11:07

Sn -----------

Well, the Tin refuses to dissolve, and just keeps on clinking about in the beaker.

I feel sure i lost a few hours watching WATER boil off from the solution after the majority of the HCl had boiled away.

Adding fresh 20% HCl gives much finer bubbles, so too much heat was certainly a mistake.

Zn ------------

The Zinc has all dissolved and has been boiled down to a brown sludge that is very hygroscopic.

(The "99% pure" claim at the top of this thread is clearly a lie. I paid for 99% and got something else.)

Trying the 'slap the solution directly onto the hotplate' trick did not work.

After some water boiled off there were some dirty brown crystals with patches of grey, and a brown Oil separated - it did not evaporate or even smoke !?!?!

Wiping the Oil with a paper towel created a big black smear of SOS on the hotplate, a bit like if it were conc sulphuric acid, yet it can't be seeing as the Barium Chloride test on the solution gave no precipitate.

----

ave's Nitric suggestion was tried with 2g of Zn powder and ~7ml of 35% HNO₃ added in 1ml portions.

NO gas immediatey forms on addition of the acid, making this a 'not-for-a-noob' route.

This Zn powder (plus whatever else is in there) formed a dense mass on one side of the beaker.

Heating caused the mass to explode in a new plume of NO gas as it cracked and the acid got to the middle of it. Amazingly it did not dissolve completely even with heating.

-------

There are so many pitfalls to what seem such simple syntheses.

I forsee an Al Suph trip coming on ...

aga - 3-10-2015 at 11:12

http://www.prepchem.com/synthesis-of-stannous-chloride/

How come i could not find that reference ?

Ah yes, lack of searching and the brains to search for the right thing !

deltaH - 3-10-2015 at 11:17

From the wiki of zinc nitrate:

Quote:

Zinc nitrate is usually prepared by dissolving zinc in nitric acid, this reaction is concentration dependent, with a reaction in concentrated acid also forming ammonium nitrate:
Zn + 2 HNO3 (diluted) → Zn(NO3)2 + H2
4 Zn + 10 HNO3 (concentrated) → 4 Zn(NO3)2 + NH4NO3 + 3 H2O
On heating, it undergoes thermal decomposition to form zinc oxide, nitrogen dioxide and oxygen.
2 Zn(NO3)2 → 2 ZnO + 4 NO2 + O2

Very interesting to see that ammonium nitrate forms!

aga - 3-10-2015 at 11:24

Sheesh ! How the f**k does that happen ?

I get it now. I've been lied to/assumed too much.

All these 'simple' equations are just a Summary of lots of complex reactions going on aren't they ?

deltaH - 3-10-2015 at 12:42

Yeah, basically because zinc is such a powerful reducing agent, it can reduce the nitrate ions into ammonia. The resulting zinc oxide then immediately reacts with nitric acid to form more zinc nitrate and water. The ammonia immediately forms ammonium nitrate.

Little_Ghost_again - 3-10-2015 at 12:55

Your wrong, but somehow I get the impression the impression your one of those I would be wasting my time explaining too, I deeply respect your knowledge and appreciate your help, but you sure can come across as an arse at times (with all due respect)

aga - 3-10-2015 at 13:00

2 sides to that.

When people who Know have to repeatedly explain the same thing, i guess it becomes frustrating, and we're all Human here (well, mostly).

blogfast25 - 3-10-2015 at 13:11

Sn -----------

Well, the Tin refuses to dissolve, and just keeps on clinking about in the beaker.

I feel sure i lost a few hours watching WATER boil off from the solution after the majority of the HCl had boiled away.

Adding fresh 20% HCl gives much finer bubbles, so too much heat was certainly a mistake.

Remember that HCl forms an azeotrope, so after a while that's what you're boiling off. You CAN'T boil off the HCl and then be left with water.

When reacting something with an acid remember that it is the temperature that affects reaction rate, not 'how fast it boils'. The boiling point of the azeotrope is constant so hard or slow boiling results in the same temperature and the same reaction rate.

It helps to do these things under reflux or partial reflux: just a simple hour glass can greatly reduce evaporative losses during the dissolution phase.

I can't vouch for your Sn, but my 99.9 % cut into small pieces dissolves reasonably quickly in simmering 37 % HCl (12 M HCl).

aga - 3-10-2015 at 13:24

The reflux thing was added to the Sn experiment after a while, and seems like good sense.

Looks very much like i've bought 2 piles of metallic crap from ebay.

One was powdered Zinc, the other a solid bar of so-called 99% Tin.

The Bar is likely 60/40 Lead/Tin solder.

The Zn powder has something Other in there.

No idea what the Other could be, yet Instinct says to stuff the Zn powder into Toluene and see what happens.

I'll leave Positive feedback for them both, as i like this sort of thing.

Much more fun than it 'just works' - you learn more when it doesn't.

blogfast25 - 3-10-2015 at 13:51

Your wrong but somehow I get the impression the impression your [sic], blah blah blah

Just how wrong I am is illustrated by the messes you keep creating in your iodine thread. Keep wasting chemicals and deluding yourself you're learning something.

[Edited on 3-10-2015 by blogfast25]

blogfast25 - 3-10-2015 at 13:53

The reflux thing was added to the Sn experiment after a while, and seems like good sense.

Looks very much like i've bought 2 piles of metallic crap from ebay.

One was powdered Zinc, the other a solid bar of so-called 99% Tin.

The Bar is likely 60/40 Lead/Tin solder.

The Zn powder has something Other in there.

No idea what the Other could be, yet Instinct says to stuff the Zn powder into Toluene and see what happens.

I'll leave Positive feedback for them both, as i like this sort of thing.

Much more fun than it 'just works' - you learn more when it doesn't.

You're quick to jump to conclusions here.

Determine the density of your Sn bar, before claiming it's lead tin solder. With lead tin solder you should probably see some poorly soluble PbCl2 precipitate, during dissolution.

Density, easy method: http://oxfordchemserve.com/density-of-solid-objects-archimed...

Re. the Zn, are you sure of the quality of the HCl? Small amounts of Fe can manifest itself when you're boiling in, even is previously you didn't find it.

[Edited on 3-10-2015 by blogfast25]

aga - 3-10-2015 at 14:06

Determining the Density of the Tin bar or the Zinc powder is painfully Obvious.

Yet i did not think to do that.

DOH !

Clear Thinkers Win again.

blogfast25 - 3-10-2015 at 14:09

Determining the Density of the Tin bar or the Zinc powder is painfully Obvious.

Yet i did not think to do that.

DOH !

Clear Thinkers Win again.

Seriously, try it. Fraudulent Fleabayers, IF that is what's happening here, deserve tar and feathers.

aga - 3-10-2015 at 14:19

Tar ?

I can make loads of that.

Any Organic Synth yields loads !

One of my dogs (alledgedly) has an affinity for feather production.

blogfast25 - 3-10-2015 at 14:52

Tar ?

I can make loads of that.

Any Organic Synth yields loads !

One of my dogs (alledgedly) has an affinity for feather production.

I suggest going through the 'proper channel' (in case of malfaisance) and not use your knowledge of the seller's address to serve 'rough justice'.

[Edited on 3-10-2015 by blogfast25]

Little_Ghost_again - 4-10-2015 at 03:17

Your wrong but somehow I get the impression the impression your [sic], blah blah blah

Just how wrong I am is illustrated by the messes you keep creating in your iodine thread. Keep wasting chemicals and deluding yourself you're learning something.

[Edited on 3-10-2015 by blogfast25]

noobs are meant to waste chemicals and make mistakes, but seems I am in good company! I might be able to salvage some of my mess, or I stand a better chance than this
http://www.sciencemadness.org/talk/viewthread.php?tid=32782

Seems knowing it all and calculating the shit ouyt of everything is no guarantee afteral.
By all means have a go at my appalling technique but be careful thats one hell of a fall from a horse that high

blogfast25 - 4-10-2015 at 05:25

Seems knowing it all and calculating the shit ouyt of everything is no guarantee afteral.

Keep the straw men coming and keep thinking you're scoring points that way: no one said anything about "knowing it all and calculating the shit ouyt [sic] of everything being a guarantee".

You don't seem to realise just how illogical you sound here: it's not a guarantee, so that's a reason for not doing it? I seem to remember your dad's a scientist, maybe you should ask him about that?

No one said anything about your technique either but in your iodine thread you seem to wilfully ignore advice from those who know how that reaction works and w/o any worthwhile results.

You must truly despise Antoine Lavoisier, considered by many the father of modern chemistry and an obsessive when it came to measuring and recording.

[Edited on 4-10-2015 by blogfast25]

Little_Ghost_again - 4-10-2015 at 06:48

you are wrong again, i didnt ignore advice, I did the experiment then posted after it went wrong, i didnt have any H2O2, its not so OTC here. I tried to follow a nurdrage video simple as that.
I have ordered more chemicals and when they arrive then I will try what was recommended. That still dosnt explain why I followed a procedure exactly like it was done and got a different result.
I would love to have the resources and chemicals like some have, but I dont and I dont have the money to get many.
I used good quality acid and the iodide was from you so the assumption is seeing as I hadnt opened it then it is what it says on the tin (so to speak).
I also figured nurdrage was highly thought of enough that his video would be fool proof. I got one to work (sort of) but low yield, the other I dont know what happened. So it isnt the case of not following peoples advice, far from it

aga - 4-10-2015 at 11:44

... why I followed a procedure exactly like it was done and got a different result

You did it different and not 100 the same i guess, or they missed out some important detail in the procedure (assuming everyone knows whatever it was) which happens a lot.

I also figured nurdrage was highly thought of enough that his video would be fool proof

Nurdrage is highly thought of. Lots of great videos.

No chemical reaction is totally foolprof.

I'm a foool, and have proven lots of simple procedures can easily fail in the wrong hands.

You really do seem to be taking all this too seriously.

So what if stuff goes wrong ?
So what if someone says something you dont like ?

aga - 4-10-2015 at 12:19

Sn----------

The Tin finally dissolved with the addition of some Nitric acid, although mild heating was also required to get a non-boring reaction rate.

Following the B25A method (blogfast25/Archimedes) the Tin bar density came out as 7.35g/cm3 which is close enough to call it pure.

The Tin is said to 99.24% pure.

There were some particles left after dissolution, so the liquid was filtered.

Gravity filtering is SLOW.

I'd switch to a vac setup, however the flow seems to continue so it will be left overnight.

Zn ---------

Looking up the ebay listing, no claim to Purity was ever made, and the Zinc powder was suggested for use in pyro applications.

Testing some powder with ethyl acetate did not get anything to separate (it was thought that some sugar or something organic was included).

Annoyed with the Brown sludge that had resulted from dissolution in 20% HCl, some NaOH was added (no LG2.485, measuring was not done here - this is like poking different sticks at a frog to see if it jumps).

Immediately some cottage cheese formed, presumably zinc hydroxide, and friends.

This was filtered, and washed with water 3 times then dunked back into a beaker.

Adding fresh HCl brought back the brown/grey liquid.

So, it goes white/grey cottage cheese in Basic conditions and brown/grey liquid in Acidic.

What happens at pH 7 ?

Start adding the sodium bicarbonate (powder).

Lots of fizzing.
The bubbles carry with them a brown oily nastiness to the top of the beaker.

Eventually, at around pH 6, the solution begins to form solid granules at the bottom and a clearer yellowish liquid in the middle, with the brown gunk as a froth on top.

Filtering yielded a yellowish clear liquid and a lot of white residue coated wth the oily material.

Yellow stuff will be boiled down tomorrow to see if it goes brown again.

Little_Ghost_again - 4-10-2015 at 12:21

... why I followed a procedure exactly like it was done and got a different result

You did it different and not 100 the same i guess, or they missed out some important detail in the procedure (assuming everyone knows whatever it was) which happens a lot.

I also figured nurdrage was highly thought of enough that his video would be fool proof

Yeah a couple of things hit a nerve and I reacted badly, for what its worth I sent an apology to blogfast. Nurdrage has two videos making iodine one was the way I did it and the other used hydrogen peroxide. I really think I added too much water or not enough acid the first time, I should have kept the liquid as I now think I could have saved it.
What I didnt count on was how bloody hard I found it to get into a container!! my gloves and jacket are black with the stuff, but despite this I did get the iodine I needed. The real kicker however was the plate came up blank after all that lol.
Thanks for the voice of reason, and appologise all round for getting petty. I got touchy because I am just not good enough at the maths for this.
I love the experimentation but I am struggling with the working out side.
Congrats on the procedure by the way.

j_sum1 - 4-10-2015 at 12:29

Tin doesn't refuse to dissolve. But it does take some patience and persuasion.
I put a pellet of Sn in a test tube with some concentrated HCl and a tiny stir bar and it rattled around for a couple of weeks, but eventually got there.

<snip> we're all Human here (well, mostly).

Implying that most of us are human, or nearly all of us are mostly human?
Just askin'

aga - 4-10-2015 at 12:30

All it needs is practice, same as Maths or anything else.

As you can see, i've failed with this Zn 'procedure' (if it can be called that) however you just need to keep marching on until it works, then you Know How.

aga - 4-10-2015 at 12:32

Quote: Originally posted by j_sum1

Implying that most of us are human, or nearly all of us are mostly human?

There are some Humans here.

That's all i can say. The rest is classssified.

blogfast25 - 4-10-2015 at 12:40

Immediately some cottage cheese formed, presumably zinc hydroxide, and friends.

This was filtered, and washed with water 3 times then dunked back into a beaker.

Adding fresh HCl brought back the brown/grey liquid.

So, it goes white/grey cottage cheese in Basic conditions and brown/grey liquid in Acidic.

What happens at pH 7 ?

It's likely that some of (all?) the brown stuff gets co-precipitated. When you redissolve, you're then back to square one.

[Edited on 4-10-2015 by blogfast25]

aga - 4-10-2015 at 12:46

DOH !

Oh well, not too much of a bother.

It's the SnCl₂ i was really after.

The ZnCl₂ was an afterthought.

Needs some actual Zinc as a starting material and not some mixed gunk.

Will still boil the pants off it tomorrow to see if it goes brown again.

blogfast25 - 4-10-2015 at 13:03

Needs some actual Zinc as a starting material and not some mixed gunk.

Will still boil the pants off it tomorrow to see if it goes brown again.

Zinc battery cases? Nicely cleaned up?

aga - 4-10-2015 at 13:25

Nah. A half kilo chunk of 99%+ Zinc sounds better.

Well, up to the point where you have to hack off a 25g chunk, then the battery casings become much more appealing as they are thinner and easier to cut.

Little_Ghost_again - 4-10-2015 at 13:28

If you have the square lantern batteries (6V) they have 4 x 1.5V cells inside, when cleaning up dead batteries these always seemed to have the better and thicker zinc in them. AAA batteries seem to have the worse (kind of make sense size wise).
The Duracell ones seemed to eat all the zinc if dead, the cheaper brand batteries that were dead had the most zinc left, just an assumption but maybe the cheapo ones have cheaper electrolyte and therefore die before the zinc is used up?
Sorry nothing to back it up except taking apart one hell of alot of them lol

[Edited on 4-10-2015 by Little_Ghost_again]

blogfast25 - 4-10-2015 at 13:59

The Duracell ones seemed to eat all the zinc if dead, the cheaper brand batteries that were dead had the most zinc left, just an assumption but maybe the cheapo ones have cheaper electrolyte and therefore die before the zinc is used up?

Virgin or near-virgin would be best, definitely.

Taking apart with care doesn't even create much of a mess.

Recovering the Mn from the filler, now that IS messy!

aga - 4-10-2015 at 14:40

Buying stuff from ebay seems equally messy.

Little_Ghost_again - 4-10-2015 at 15:43

Virgin or near-virgin would be best, definitely.

If you find a supply give me a shout

aga - 5-10-2015 at 09:03

Lemon Curd.

That's what the SnCl2 solution looks like after being boiled down a bit, complete witha slight frothiness on top.

Currently it is sitting in the lab fridge, hopefully forming non-lemon-curdy crystals.

The Zn solution is a complete failure - all i can get is Table Salt crystals out of it now.

aga - 7-10-2015 at 14:08

Well, tossing the Zinc failure was probably a good idea.

The Tin Chloride went all Yellow and Thick.

Despite a few hot filtrations it remains yellow.

Leaving the light on in the shed overnight was a mistake.

The 'camoflage' moths come at this time every year.
I imagine it is the Male, who has mated already and just finds somewhere to die, which they always do.

This year they have very muted colours - usually they have bright red and orange colours.

Diluting and filtering out the wildlife for the photo, THAT abomination is supposed to be Tin Chloride !

Closest colour match is the FeCl₄- ion as per some website i cannot find today.

I think i will boil down some of my 20% HCl and see if it responds to the iron tests i have.

It shows no iron content in it's current concentration.

[Edited on 7-10-2015 by aga]

blogfast25 - 7-10-2015 at 15:59

Closest colour match is the FeCl₄- ion as per some website i cannot find today.

I think i will boil down some of my 20% HCl and see if it responds to the iron tests i have.

It shows no iron content in it's current concentration.

Forget about iron, I'd put good money on there not being any.

Have you checked the solubility of the 'kurd'? If it doesn't dissolve to a clear solution you've got a problem of hydrolysis: basic chlorides having been formed. If it does dissolve fully your product is good to go.

Highly soluble chlorides often don't form well-formed crystals.

[Edited on 8-10-2015 by blogfast25]

aga - 8-10-2015 at 07:37

Soluble in water ?

If it is tin hydroxide/tin oxide, should i boil it down to a thick curd then bubble HCl gas through it for example, or is starting again with less water the sane way to go ?

blogfast25 - 8-10-2015 at 07:44

Soluble in water ?

If it is tin hydroxide/tin oxide, should i boil it down to a thick curd then bubble HCl gas through it for example, or is starting again with less water the sane way to go ?

For once, do as you're told!

Take a pinch of the kurdy stuff and see if it dissolves in a bit of water. Add a drop of acid to the water to make sure its pH < 7. Observe and report.

aga - 9-10-2015 at 10:56

For once, do as you're told !

Yesbas.

No, the curdy stuff just goes into a milky yellow suspension/thin bannana milkshake on addition of water.

pH is around 1 already.

blogfast25 - 9-10-2015 at 13:14

No, the curdy stuff just goes into a milky yellow suspension/thin bannana milkshake on addition of water.

pH is around 1 already.

Ok, that's hydrolysis for sure. Seems hard to avoid with SnCl2 dihydrate though I did make some that was fine. I also bought a batch for resale a couple of years back and it too was 'bad'.

[Edited on 9-10-2015 by blogfast25]

aga - 9-10-2015 at 13:16

Ok, that's hydrolysis for sure.

So what is it after hydrolysis ?

Tin Hydroxide ?

More to the point, is it recoverable ?

I get the feeling that whacking some Cl₂ into some elemental Tin would be easier.

deltaH - 9-10-2015 at 13:19

The tin dioxide should be easy to dissolve by adding in conc. HCl, but then you will have a solution either just contaminated with hexachlorostannic acid or mostly that, in short, tin in the 4+ oxidation state that needs to be reduced to 2+. If you're going to reduce this solution with tin metal, keep the pH around -0.5 at all times and put suitable loose fitting plastic lid so that it doesn't get undue exposure to air or you might end up in the same boat all over again (or even better, film plastic with a needle hole pricked in it as a vent) if you're leaving it for days open.

As for the colour, once you get the tin dioxide dissolved, simply stir your solution with a few grams of activated charcoal for several minutes, then filter. It might help

Actually isolating stannous chloride crystals from you liquor after reduction might just prove too much of a pain. Use the solution as is... you want it as a gold indicator right?

[Edited on 9-10-2015 by deltaH]

aga - 9-10-2015 at 13:29

Yes, it is for a Gold indicator, so may be OK as-is.

However it HAS to become crystals, as that was the original objective.

I shit ye not : there WILL be SnCl₂.2 H₂O crystals around here some day soon.

Still got about 400g Sn left, and it has absolutely no choice in the matter.

[Edited on 9-10-2015 by aga]

blogfast25 - 9-10-2015 at 13:38

The tin dioxide should be easy to dissolve by adding in conc. HCl, but then you will have a solution either just contaminated with hexachlorostannic acid or mostly that, in short, tin in the 4+ oxidation state that needs to be reduced to 2+. If you're going to reduce this solution with tin metal, keep the pH around -0.5 at all times and put suitable loose fitting plastic lid so that it doesn't get undue exposure to air or you might end up in the same boat all over again (or even better, film plastic with a needle hole pricked in it as a vent) if you're leaving it for days open.

What he has is not primarily SnO2, the Sn(+2) will have partially oxidised to Sn(+4) by air but only partially. Real SnO2 is incredibly insoluble and stubborn, it hardly responds to HCl at all.

I know this from personal experience: a bad batch of SnCl2 didn't even dissolve in 12 M HCl. Only on slowly and carefully adding cold H2O2 with intermittent cooling was a clear solution of H2SnCl6 obtained.

And yes, you can then reduce that back to SnCl2 with metallic Sn. That solution should be good enough for gold testing, without crystallising it.

[Edited on 9-10-2015 by blogfast25]

aga - 9-10-2015 at 13:43

Peroxide going in the pot shortly.

Followed by a 400g block of Sn.

YeeHar !

There's Tin in them thar hills !

aga - 9-10-2015 at 14:09

A squirt of H₂O₂ did the trick, even at just 3%.

Adding the cold lump of Tin metal took up most of the heat - no boiling or anything - the bar is a bit warm, and went a bit black.

Before LG2.373b says anything, No measurements were made.

blogfast25 - 9-10-2015 at 14:17

Best to leave it stand overnight with the ingot in it, to ensure full reduction back to Sn(+2). The bottle it and put a few Sn chips in with the solution. It will keep it 'always' as Sn(+2).

aga - 9-10-2015 at 14:20

Yesbas.

I'll try direct element combination over the weekend to see if i can get crystals, dust, an explosion - anything !

At some point soon there WILL be crystals.

There is no option - Giving Up at the first hurdle is just, well, Feeble.

[Edited on 9-10-2015 by aga]

[Edited on 9-10-2015 by aga]

deltaH - 9-10-2015 at 21:46

Ah ok, cool, I'm happy it all worked out for aga. I also have a rather large bar of supposedly very pure tin that I should convert at some stage. I'm curious if this yellow curds is a universal behaviour.

blogfast25 - 10-10-2015 at 06:16

Funny that, I was thinking that too. I seem to recall having obtained some SnCl2 dihydrate crystals that were colourless.

There isn't much in the Sn2+ [Kr] 4d105s2 electron configuration that would point to colour.

[Edited on 10-10-2015 by blogfast25]

S.C. Wack - 10-10-2015 at 08:23