Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: biggermens on August 14, 2014, 11:42:49 PM
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Hello everyone :)
I am making Zink sulfate by dissolving Zink in sulfuric acid, and then letting the Zink sulfate grow in to crystals
Then i filter off the Zink sulfate crystals with paper filter, but then how can i dry off the crystals 100% Dry ???
Thanks
biggs
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Hi Biggs :)
You can either put them under high vacuum or heat in an oven, or even combine the two and use a vacuum oven. Do you have access to any of these?
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You can also wash them with a solvent that won't dissolve the crystals and that evaporates more easily than sulfuric acid.
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I don't really have a vacuum , all i have is a little hand pump but i have a small toaster oven i can use hehe, all i have is a aluminum pan for that, i am scared i destroy the pan and contaminate my zink sulfate, What type of solvent would not dissolve the zink sulfate ?
Is there a better way to make Zink sulfate with out using copper sulfate ???
I just dissolve some Zink strips last night and i did not get any crystals :((
Thanks lots
Biggs
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Zinc sulfate is decently soluble, and crystals won't form just from dissolving zinc in sulfuric acid. What I would do is: Boil down the solution until you see crystals forming, then let it cool.
According to Wikipedia [http://en.wikipedia.org/wiki/Solubility_table#Z (http://en.wikipedia.org/wiki/Solubility_table#Z)] 60.5 grams will dissolve in 100 mLs of water at 100°C, and 41.6 grams at 0°C.
So if you cool it properly, assuming 100% recovery yields, and assuming you cool it as soon as you see the first crystals, you should get over 30% of the sulfate as nice crystals - which will be easy to filter.
If you want the rest, you'll need to boil off the rest of the water (and residual sulfuric acid), which will leave you with a less pure powder, which you may want to recrystallize for better purity.
The powder will contain sulfuric acid still, which will be hard to boil off, 3 hours in a conventional oven at 200°C should do as good a job as you could do at home.
You can also wash them with a solvent that won't dissolve the crystals and that evaporates more easily than sulfuric acid.
This will work fine if you have a solvent which fits the required criteria.
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Or you could dry it as much as you can, rinse away the sulfuric acid with water (and losing some zinc sulfate.) Then, you can recrystallize, if you need the purest crystals. You seem to be asking for the very best purity, and possible want the greatest possible yields, and you only have kitchen equipment to work with. You should realize that you're asking for too much. What do you need this reagent for? Why not simply buy it from a chemical supplier? How pure do you need it? And how much do you need?
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I don't think it has to be super pure, i am just using it to Zink plate nuts, bolts and motorcycle parts, i had a little system that was working well :) but i find it takes for ever for it to dry, I it very hard to buy zink sulfate in Canada unless your a school of some lab, they just don't sell it to anyone up here :( So i am making it :)
I don't mind buying equipment to make things easier and or better :-D
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Theoretically, if you've made zinc sulfate by dissolving zinc in dilute sulfuric acid, there will always be some sulfuric acid left over after drying, because its not as volatile as water, and won't "dry away." You could have added less acid, then if you had zinc left over, you'd be sure the acid was gone. Then you'd filter the solid away, and dry. But you can still rinse your dried solid with a tiny amount of water. Just keep rinsing a little and drying. Once its dried, you'll know you've gotten rid of the sulfuric acid, and some of your zinc sulfate too, unfortunately.
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With the help of everyone on here i got me a little system going good :)
I vacuum filter it then i put it in a little oven it works grate :)
But one batch i left it in a tad to long and it turn a little brown,
Do anyone know if its still good to use for my zinc plating solution ???
Thanks
Biggs
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I would recrystallize just to be sure. Hard to know why its brown. I can't think of any compound off hand that would be brown. Possibly there's a trace of organic material that charred. If you're in the mood to experiment, you could heat in the oven some more. Unless your oven reaches 770 °C (look that up for Fahrenheit, you'll see its not likely) you shouldn't decompose zinc sulfate. From what I know of plating, removing trace organics is important for plating efficiency. You may see an improvement.
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I will do that :)
I will dissolve it re filter it and recrystallize it and see what will happen :)
Thanks a bunch :)
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After i am done cooking the zinc sulfate it turns in to a white powder, That should be ok ?
Thanks
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https://en.wikipedia.org/wiki/Zinc_sulfate
The above is just to add information to the thread for further understanding