Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Abhi75 on November 05, 2021, 05:15:26 AM
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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?
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https://en.wikipedia.org/wiki/Magnesium_sulfate
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.
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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
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Crucible or Pyrex glass, sand bath.
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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...😅