Presto
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Report Thread starter 11 months ago
#1
Need help understanding these equations please
Can someone please clear my doubts?

1) The first equation is deprotonation right?
2) Is there a concept or a reason the first reaction occurs like this or am I supposed to learn it as it is?
3) I know this second reaction is ligand exchange but where did the H2O from the initial ppt go? Is this reaction even correct?
4) I also don't get why the precipitate in the 2nd one dissolves. Can someone please explain this too?

Last edited by Presto; 11 months ago
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BobbJo
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Report 11 months ago
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1. Yes it is an acid-base reaction. [Cr(H2O)6]3+ is donating protons to NH3. NH3 acts as a base here.
2. The grey green ppt is chromium(III) hydroxide, [Cr(H2O)3(OH)3]. It is uncharged so it is insoluble. When the neutral complex is formed, you see a ppt
3. The reaction is not balanced.
4. [Cr(NH3)6]3+ is charged and soluble. NH3 acts as a ligand here.
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Presto
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#3
Report Thread starter 11 months ago
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(Original post by BobbJo)
1. Yes it is an acid-base reaction. [Cr(H2O)6]3+ is donating protons to NH3. NH3 acts as a base here.
2. The grey green ppt is chromium(III) hydroxide, [Cr(H2O)3(OH)3]. It is uncharged so it is insoluble. When the neutral complex is formed, you see a ppt
3. The reaction is not balanced.
4. [Cr(NH3)6]3+ is charged and soluble. NH3 acts as a ligand here.
Thank you!
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