username2207531
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There's a question on my homework about qualitative testing with transition metals. Here is the one that confuses me:

When ammonia is added dropwise to B, a pale pink precipitate forms, which does not redissolve in excess ammonia.

So obviously the ion in Mn2+, but I can't figure out how that would work!
Pale pink compounds are MnO, MnCl2 and MnCO3, so how would one be made with ammonia?
The only Mn2+ precipitation reactions we were taught about are ligand substitutions, and they all make a dark brown precipitate.
I need to write ionic equations for the reaction.

Thanks!
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111davey1
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(Original post by JustJusty)
There's a question on my homework about qualitative testing with transition metals. Here is the one that confuses me:

When ammonia is added dropwise to B, a pale pink precipitate forms, which does not redissolve in excess ammonia.

So obviously the ion in Mn2+, but I can't figure out how that would work!
Pale pink compounds are MnO, MnCl2 and MnCO3, so how would one be made with ammonia?
The only Mn2+ precipitation reactions we were taught about are ligand substitutions, and they all make a dark brown precipitate.
I need to write ionic equations for the reaction.

Thanks!
Just the same reaction as if you add say NaOH so Mn2+ + 2OH- --> Mn(OH)2 Dont take my word for it though
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username2207531
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(Original post by 111davey1)
Just the same reaction as if you add say NaOH so Mn2+ + 2OH- --> Mn(OH)2
That was my initial thought, but it says everywhere that Mn(OH)2 is pure white. Or is that just because it's very pale?
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111davey1
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(Original post by JustJusty)
That was my initial thought, but it says everywhere that Mn(OH)2 is pure white. Or is that just because it's very pale?
If you add ammonia dropwise the reaction above should happen so Mn(OH)2 would form which would have to be pale pink. If you add excess of ammonia a substitution reaction would occur producing a brown precipitate.
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username2207531
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(Original post by 111davey1)
If you add ammonia dropwise the reaction above should happen so Mn(OH)2 would form which would have to be pale pink. If you add excess of ammonia a substitution reaction would occur producing a brown precipitate.
Thanks!
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