Titration with Carbonates acting as bases

[Kushal]

Homework Statement

when a carbonate acts as a base and neutralises an acid, CO2 is formed. the problem is that some of the CO2 dissolves in the water and forms Carbonic Acid.the Carbonic acid will affect the titre value as it will react with the base, along with the HCl. How do we prevent this to happen?

Homework Equations

Na2CO3 + HCl -----> 2NaCl + CO2 + H2O

CO2 + H2O ------> H2CO3

The Attempt at a Solution

what I'm thinking of is that, by heating the flask containing the titrating mixture as the titration is performed, the CO2 may dissolve out of the water...

Is it a good solution? If you have any other suggestion, let me know,

 

[Stevedye56]

Is there any way that you could think of that could throw off the equlibrium?

 

[Kushal]

Is there any way that you could think of that could throw off the equlibrium?

Yeah, you're right; i can eliminate the CO2 by just added a lil' bit more of the Na2CO3...

thnx...

but the heat thing also works perfect, since solubility of a gas decreases with increase in temperature.

 

[chemisttree]

Yeah, you're right; i can eliminate the CO2 by just added a lil' bit more of the Na2CO3...

This won't work. You are titrating an unknown amount of carbonate with an acid. Adding additional carbonate will skew your results.

The heating idea is good. Sparging or vacuum degassing also works.

 

[Stevedye56]

Heating is probably your best bet. It will be the simplest for you unelss you are just doing the problem for homework. Then you could just mention the various ways.

 

[Kushal]

hey chemisttree can you explain to me in more detail why the saturation of the solution with the carbonate won't work...

 

[chemisttree]

hey chemisttree can you explain to me in more detail why the saturation of the solution with the carbonate won't work...

Well, you ARE trying to titrate an unknown amount of carbonate. How will adding additional carbonate help you with that?