beeludwig
Harmless
Posts: 30
Registered: 7-5-2019
Member Is Offline
|
|
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
|
|
DraconicAcid
International Hazard
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 4301
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
|
|
Admagistr
Hazard to Others
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 350
Registered: 4-11-2021
Location: Central Europe
Member Is Offline
Mood: The dreaming alchemist
|
|
Quote: Originally posted by beeludwig ![](images/xpblue/lastpost.gif) | 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]
|
|
unionised
International Hazard
![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif) ![*](images/xpblue/star.gif)
Posts: 5109
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
Use pH paper.
The strongly acidic one is alum. The alkaline one is Sod. citrate and the near neutral one is Epsom salts.
|
|