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Topic: how come Mg(NO3)2 is acidic?  (Read 21734 times)

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Offline Faisal

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how come Mg(NO3)2 is acidic?
« on: March 02, 2008, 04:05:12 PM »
k I understand how to find out whether salts r acidic or basic BUT how come
Mg(NO3)2 is acidic.Okay NO3 is from a strong acid but isn't MG from a strong base
which is Mg(OH)2...shudn't the salt be neutral instead of acidic.thx in advance
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Offline Borek

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Re: how come Mg(NO3)2 is acidic?
« Reply #1 on: March 02, 2008, 04:34:44 PM »
What is Mg(OH)2 solubility?
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Offline Faisal

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Re: how come Mg(NO3)2 is acidic?
« Reply #2 on: March 02, 2008, 10:36:17 PM »
quite high...right?wht does solubility have to do with this?
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Offline AWK

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Re: how come Mg(NO3)2 is acidic?
« Reply #3 on: March 03, 2008, 01:40:01 AM »
Quote from: Faisal on March 02, 2008, 04:05:12 PM
k I understand how to find out whether salts r acidic or basic BUT how come
Mg(NO3)2 is acidic.Okay NO3 is from a strong acid but isn't MG from a strong base
which is Mg(OH)2...shudn't the salt be neutral instead of acidic.thx in advance
In the case of hydrated metal cations there are two equivalents method of calcultaiting your problem.
You can write down a reaction:
Me(H2O)nm+ + H2O = Me(H2O)n-1OH(m-1)+ + H3O+
whixh is equivalent to formation of covalent bond of OH- with metal cation (complex formation)
Mem+ + 2H2O = Me(m-1)+OH + H3O+
At these cases we use a Bronsted protolysis constant in the first case or complex formation constant equivalent to it (log Kf= 2.58 for Mg2+)
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Offline Faisal

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Re: how come Mg(NO3)2 is acidic?
« Reply #4 on: March 03, 2008, 02:19:55 AM »
Quote
In the case of hydrated metal cations there are two equivalents method of calcultaiting your problem.
You can write down a reaction:
Me(H2O)nm+ + H2O = Me(H2O)n-1OH(m-1)+ + H3O+
whixh is equivalent to formation of covalent bond of OH- with metal cation (complex formation)
Mem+ + 2H2O = Me(m-1)+OH + H3O+
At these cases we use a Bronsted protolysis constant in the first case or complex formation constant equivalent to it (log Kf= 2.58 for Mg2+)
HUH?!?!?I am sooo confused and lost...can u plz be a bit simpler and use an easier and more detailed explanation.What is Me?What is bronsted protolysis???
thank you
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Offline gibouleau

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Re: how come Mg(NO3)2 is acidic?
« Reply #5 on: March 04, 2008, 11:42:04 PM »
isnt Mg(OH2)2(s) ??
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Offline AWK

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Re: how come Mg(NO3)2 is acidic?
« Reply #6 on: March 05, 2008, 01:17:47 AM »
Treat it as rule - all hydrated cations Me(H2O)n with n 4-6 are weak acids of the acidity comparable with simple carboxylic acids.
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Offline LQ43

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Re: how come Mg(NO3)2 is acidic?
« Reply #7 on: March 05, 2008, 03:03:10 PM »
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