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Reaction between Ca(CH3COO) and NaHCO3


observer1

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The reaction between Ca(CH3COO)2 + Na2CO3 ---> CaCO3 + 2CH3COONa
But why can't the same displacement reaction happen when NaHCO3 is added to Ca(CH3COO)2
Why does it show that no reaction happens when they are mixed?                                                                                                                   (type it in google)

Edited by observer1
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4 hours ago, observer1 said:

The reaction between Ca(CH3COO)2 + Na2CO3 ---> CaCO3 + 2CH3COONa
But why can't the same displacement reaction happen when NaHCO3 is added to Ca(CH3COO)2
Why does it show that no reaction happens when they are mixed?                                                                                                                   (type it in google)

You don't seem to be taking in the content of previous replies on this matter. 

1) CaCO3 is largely insoluble. So a solution of ions containing Ca²⁺ and CO3²⁻ will precipitate out CaCO3. So that's why that one happens. As I explained before, if all the combinations of salts are soluble, all you get is a mixture of dissolved ions, as there is nothing to cause one compound to separate from the mixture. 

2) Ca(HCO3)₂ does not exist in the solid state, as I pointed out on one of your previous threads. https://en.wikipedia.org/wiki/Calcium_bicarbonate

If you want to know why it does not exist, that's a more complicated question, though we could discuss the reasons. My guess is it will be due to the difficulty in accommodating 2 large monovalent anions in a crystal structure with one smallish divalent cation. In other words the lattice energy is expected to be low, making formation of this compound in the solid phase energetically unattractive, relative to other options.

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1 hour ago, chenbeier said:

One thing more

Ca(CH3COO)2 + NaHCO3 ---> CaCO3 + CH3COONa +CH3COOH!!!!

Acetic acid is to acidic that this reaction appears. It would work in opposit direction more or less.

 

Not sure I follow this. Do you mean that because acetic acid is a weak acid, an aqueous solution of any acetate will be mostly in the form of undissociated acetic acid, thus making acetate salts net absorbers of H+ ions -  and therefore basic?

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3 hours ago, chenbeier said:

No,

compare the acidity or the pKa of NaHCO3 and CH3COOH

Who will win the game if mixed. In my opinion Hydrogen carbonate is not able to expell acetic acid. The opposit is the case. Even CO2 development takes place.

OK, pKa of acetic acid is lower, so acetate will not tend to abstract H+ from HCO3-.  Ah, so what you mean is that acetic acid would protonate HCO3-, leading to formation of carbonic acid, which then decomposes to CO2 and water. Yes, indeed. But what he have here is acetate not acetic acid. So I'm still not quite following you.

Edited by exchemist
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We have acetate in this case the Calcium acetate and sodium hydrogen carbonate. To get Calciumcarbonate the sodium and the hydogen has to react with the acetate. This means sodium acetate and acetic acid has to be built. But Acetic acid will not get built because it would react directly with carbonate to CO2 back. So calcium acetate will remain.

Ca(CH3COO)2 + NaHCO3 ---> CaCO3 + CH3COONa +CH3COOH!!!!

This will not happen.

 

 

Edited by chenbeier
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