beeludwig
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Potassium Alum vs MgSulfate vs sodium citrate
One of my students made a solutions, magnesium sulfate, potassium alum, and sodium citrate and forgot to label. While I'm mildly annoyed, the issue
is now is there a quick and easy way to figure out which is which
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DraconicAcid
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Add base. Sodium citrate will do nothing.
Magnesium sulphate will give a precipitate of Mg(OH)2
Potassium alum will give a gelatinous precipitate of Al(OH)3, which dissolves with excess hydroxide.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Admagistr
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Quote: Originally posted by beeludwig  | | One of my students made a solutions, magnesium sulfate, potassium alum, and sodium citrate and forgot to label. While I'm mildly annoyed, the issue
is now is there a quick and easy way to figure out which is which |
It is exactly as DraconicAcid writes.Use alkaline hydroxide NaOH,KOH,do not use ammonia solution! Al(OH)3 will not dissolve
in excess NH4OH.Put samples in 3 tubes and add NaOH,or KOH solution drop by drop,Al(OH)3,or AlOOH will dissolve to NaAl(OH)4,or KAl(OH)4 in
excess NaOH,or KOH.
[Edited on 18-2-2023 by Admagistr]
[Edited on 18-2-2023 by Admagistr]
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unionised
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Use pH paper.
The strongly acidic one is alum. The alkaline one is Sod. citrate and the near neutral one is Epsom salts.
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