vampirexevipex
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Reaction of NH4OH and MgSO4
I recently reacted 10% ammonia and magnesium sulfate to make magnesium hydroxide as said in this sites:
http://answers.yahoo.com/question/index?qid=20080527213702AA...
http://answers.yahoo.com/question/index?qid=20080422014114AA...
http://www.youtube.com/watch?v=32QrNqqwXQw
The only sites i could find, and all of them say that it makes magnesium hydroxide... but... all i got was a clear solution with alot of bubbles (The
magnesium sulfate reacted almost instantly to dissolve in the aqueous ammonia). Could the ammonium sulfate made in the solution reacted with the
magnesium? The solution's Ph was above 7.5.
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Hexavalent
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Were you attempting this specific reaction or just looking for a way to make magnesium hydroxide?
If the latter, then any soluble hydroxide - e.g. NaOH, KOH etc. will do the trick when combined with aqueous MgSO4 to yield magnesium
hydroxide.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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vampirexevipex
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Quote: Originally posted by Hexavalent  | Were you attempting this specific reaction or just looking for a way to make magnesium hydroxide?
If the latter, then any soluble hydroxide - e.g. NaOH, KOH etc. will do the trick when combined with aqueous MgSO4 to yield magnesium
hydroxide. |
Thanks but i was just attempting to make this specific reaction, so, do you know what happened?
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Hexavalent
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Did you add the solid MgSO4 as a solid to the ammonia?
Try making a solution of it and trying again...maybe even in a small test tube to conserve chemicals.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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vampirexevipex
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Yes, i added the sulfate as a solid. And to make it again.. erhhmmm ill have to buy some more MgSO4 cause i spend it all in the solution  . But, what really happened there? Im curious
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AndersHoveland
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magnesium sulfate reacts with sodium bicarbonate to form a milky magnesium carbonate precipitate, slowly and continuously giving off little bubbles of
carbon dioxide.
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sargent1015
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| Quote: Originally posted by AndersHoveland | | magnesium sulfate reacts with sodium bicarbonate to form a milky magnesium carbonate precipitate, slowly and continuously giving off little bubbles of
carbon dioxide. |
Actually he didn't add any bicarb, he added ammonia.
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weiming1998
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This reaction is a very simple double displacement reaction.
First: NH3+H2O<--->NH4(+)+OH-. This equilibrium leans to the left under usual conditions, but the removal of either OH- ions or NH4+ ions shifts
it to the right.
Then MgSO4--->Mg(2+)+SO4(2-).
The Mg2+ ions reacts with the OH- ions to form insoluble Mg(OH)2, removing the OH- ions from solution and causing the equilibrium to shift to the
right. The products would be Mg(OH)2, NH4+ ions and SO4(2-) ions. Filter and dry leaves you with Mg(OH)2 and (NH4)2SO4.
I don't understand the controversy in such a simple reaction.
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francis
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| Quote: Originally posted by weiming1998 | This reaction is a very simple double displacement reaction.
First: NH3+H2O<--->NH4(+)+OH-. This equilibrium leans to the left under usual conditions, but the removal of either OH- ions or NH4+ ions shifts
it to the right [....]
I don't understand the controversy in such a simple reaction. |
I think the controversy is because it didn't apparently work.
The reason it didn't seem to work is because the OH- ion concentration was too low: the 10% ammonia does not have appreciable [-OH] to form a visible
Mg(OH)2 ppt.
If you dropped the pH to coax more NH4(+) to form, the OH produced according to the equilibrium listed by the previous poster would immediately be
protonated and therefore be unavailable for reaction.
If the raised the pH above ~9 then added the MgSO4, there's no point having NH3 present at all (because the rxn occurs through the OH- ion, which
would have been formed from addition of the stronger base, whatever it was, that you used to raise the pH).
The only way this reaction will work to a visible extent, is if you use a higher concentration NH3 solution than 10%, so that a higher amount of OH-
is formed (i.e. the solution is more basic - pH 7.5 won't do it. It's just like adding MgSO4 to water).
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barley81
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Or, use cheap NaOH instead of ammonia. You will get higher yield based on both ammonia and magnesium sulfate and avoid the use of (sometimes)
expensive, smelly 25% NH<sub>3</sub>. A suspension of magnesium hydroxide has a pH of 10.5, so you need a stronger base than ammonia to
precipitate most of the magnesium.
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