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Topic: Converting magnesium sulphate heptahydrate to anhydrous magnesium sulphate  (Read 1031 times)

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Offline Abhi75

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How can I convert magnesium sulphate heptahydrate to its anhydrous form? I am planning to heat a few grams of the salt in a small bone china bowl over bunsen burner. Can someone tell me how much heat and time is needed to do so?

Offline Orcio_87

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Re: Converting magnesium sulphate heptahydrate to anhydrous magnesium sulphate
« Reply #1 on: November 05, 2021, 09:12:07 AM »
https://en.wikipedia.org/wiki/Magnesium_sulfate
Quote
The monohydrate can be prepared by heating the hexahydrate to approximately 150 °C. Further heating to approximately 300–320 °C gives anhydrous magnesium sulfate.

I think that heating till it will be glowing red for about 5-10 min. should be enough.

Be carefull not to overheat, as it decomposes without melting to MgO and SO3.

Offline Abhi75

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Re: Converting magnesium sulphate heptahydrate to anhydrous magnesium sulphate
« Reply #2 on: November 06, 2021, 12:46:48 AM »
My bone china bowl cracked within few minutes of heating and a lot of salt got stuck to the bowl and so it was hard to recover all of the salt. I also noticed that the weight of salt reduced from 2 grams to almost 1.2 grams... which means that some amount of salt had transformed to atleast monohydrate by the time bowl cracked...
Can someone suggest a good container for heating and how can i raise the temperature very slowly so that i have time to stir the salt to prevent it from sticking or burning/decomposing

Offline Borek

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Re: Converting magnesium sulphate heptahydrate to anhydrous magnesium sulphate
« Reply #3 on: November 06, 2021, 03:50:29 AM »
Crucible or Pyrex glass, sand bath.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline Abhi75

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Re: Converting magnesium sulphate heptahydrate to anhydrous magnesium sulphate
« Reply #4 on: November 06, 2021, 08:18:15 AM »
Thanks a lot... will give it a try...
Today i was able to remove a lot of water from heptahydrate... but it would have been less tiring and more efficient if I had used something from your suggestion cuz the 50ml beaker i used broke apart when i tried to pry out solid salt at its bottom...😅

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