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Topic: How does this reaction work? (Ammonia with Silver)  (Read 40380 times)

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VenDiddy

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How does this reaction work? (Ammonia with Silver)
« on: May 09, 2005, 07:24:14 PM »
Question:
Excess concentrated aqueous ammonia is added to solid silver chloride.

Answer:
AgCl + NH3 => Ag(NH3)2+1 + Cl-

Can someone please explain why this works?  ???
« Last Edit: May 09, 2005, 08:33:12 PM by VenDiddy »

Grumples

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #1 on: May 09, 2005, 08:19:42 PM »
By the way, I believe it forms Ag(NH3)2+1, not +2.  Sorry, but all I know is that it forms, not how.  However, I think it may have to do with the N from the NH3 (which is slightly negative) being attracted to the Ag+1 ion.

VenDiddy

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #2 on: May 09, 2005, 08:34:10 PM »
Just corrected the charge. Chemistry baffles me...

Offline xiankai

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #3 on: May 10, 2005, 06:05:14 AM »
i also asked a similar question last time, its just that  it forms a complex salt . as for why it forms a complex salt... well maybe ammonia could be more concentrated and hence displaces chlorine and forms the unstable salt with silver... just my thoughts
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Offline AWK

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #4 on: May 10, 2005, 07:58:10 AM »
Quote
and hence displaces chlorine and forms the unstable salt with silver... just my thoughts
Silver cholride itself is insoluble in water, though is ionic in solid state.
After addition of ammnia complex Ag+ forms complex cation Ag(NH3)2+i and this new compund
Ag(NH3)2+Cl- is soluble in water.
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Offline jdurg

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #5 on: May 10, 2005, 05:22:32 PM »
AgCl is VERY slightly solube in water (But it's such a small solubility number that we basically just say 'it's insoluble').  So by removing the Ag+ ions from the water, you shift the equillibrium which allows more AgCl to dissolve, so more Ag+ is formed which is then eaten up again, etc. etc.
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Offline Donaldson Tan

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Re:How does this reaction work? (Ammonia with Silver)
« Reply #6 on: May 11, 2005, 12:05:03 AM »
1. AgCl (s) <-> Ag+ (aq) + Cl- (aq)

2. Ag+ + 2NH3 <-> Ag(NH3)2+

equilibirum 2 has a very high Kstability constant. effectively, adding concentrated ammonia removes Ag+ in solution because Ag+ is converted to another form. This favours the forward reaction (Le Chatelier's Principle) of Equlibrium 1. The net effect is AgCl exhibits higher solubility in concentrated ammonia.
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