Jump to content

which displacement reaction?


observer1

Recommended Posts

21 hours ago, observer1 said:

Ca(CH3COO)2 + 2NaOH ---> 2CH3COONa + Ca(OH)2
or
2CH3COONa + Ca(OH)2 ---> Ca(CH3COO)2 + 2NaOH

You have asked this type of question several times now and the answer has been the same in all cases: consider the solubility of the possible combinations of ions. There is an article in Wiki on this: https://en.wikipedia.org/wiki/Salt_metathesis_reaction Note especially the section on counterion exchange, which is what your questions have been about.

There is also a link in the article to a quite useful solubility chart, which is helpful if one does not know whether a given ionic compound is appreciably water-soluble or not: https://en.wikipedia.org/wiki/Solubility_chart

 

 

 

Link to comment
Share on other sites

The table is understandable

If you check Ca with OH it says sS and Ca with CO3 also sS, slightly solouble, if you do it with Na its says s solouble. The same with acetate.

So if you mix sodium carbonate and Calcium acetate , both solouble alone, then you will find a precipitation takes place , because the CaCO3 is formed.

The same takes place  if you take Calcium acetate and sodium hydroxide. Ca(OH)2 is formed. The opposit reaction dont takes place, because one reacting is not good solouble.

Link to comment
Share on other sites

2 hours ago, observer1 said:

That, frankly, is all I understood form the https://en.wikipedia.org/wiki/Solubility_chart link u sent.
I was specifically looking about this reaction and that was the only difference I found(from the table u sent)

if you can, can you pls explain this in a much simpler was or give a video for it?

No need for a video, you just need to be able to read and take in what you have already been told, several times now.

You get a double displacement reaction when one of the possible combinations is insoluble, because it is more stable in the solid state than in solution, and therefore precipitates out. I've told you this, so has @chenbeier, and it is repeated in the Wiki link I went to the trouble of providing. 

In your latest example it is Ca(OH)₂ that is much less soluble than the other possibilities, so it will precipitate from any solution with those ions in it.

 

Edited by exchemist
Link to comment
Share on other sites

so since Ca(OH)2 is slightly soluble and not completely, the reaction is not possible

10 minutes ago, exchemist said:

You get a double displacement reaction when one of the possible combinations is insoluble, because it is more stable in the solid state than in solution, and therefore precipitates out

now i understand
so, just asking, let's ASSUME Ca(OH)2 is also soluble, then the reaction will go back and forth?

Link to comment
Share on other sites

Let say you mix Calcium acetate and sodium chloride

Both salts are solouble, you will get everything dissolved and have Ca2+ , CH3COO-, Na+ and Cl - in solution. No reaction.

The same you would get if you mix Calciumchloride with sodium acetate.

Link to comment
Share on other sites

so in a reaction, if both the reactants and products are soluble in water, the reaction does not take place while if the product is not completely soluble in water, then the reaction is possible. Also if the reactants are no soluble in water, the reaction does not take place

Link to comment
Share on other sites

You start from a situation, where two compounds are soluble.  If a new compound is formed, which  is unsoluble, then the two reactants react each other.  If New compounds also soluble nothing will be observed. If a reactant is not soluble then also no reaction takes place.

For example Ca(CH3COO)2 + NaHCO3 I change my opinion. In long term also a reaction takes place, because NaHCO3 was called sodium bi carbonate, today sodium hydrogen carbonate. Bi means two, what gives the following 2 NaHCO3 => Na2CO3 + H2CO3.

H2CO3 => H2O + CO2

So if this is given to the calcium acetate, then

Ca(CH3COO)2 + 2 NaHCO3 => CaCO3 + 2 CH3COONa + H2O + CO2

 

Edited by chenbeier
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.