[Burian]

If I put some calcium carbonate into the adequate phosphoric acid solution, the resulting CO2 gas will be released from the solution. The confusion is whether all the resulting CO2 gas excape from the solution.
If there is still some residual gas in solution, how to push them away from the solution? Or to determine the amount of residual？

[Borek]

Define "all". Carbon dioxide dissolves in liquids as every other gas. Adding acid you can convert carbonates to carbon dioxide, but you will not get rid of "just" dissolved CO₂.

[Burian]

Define "all". Carbon dioxide dissolves in liquids as every other gas. Adding acid you can convert carbonates to carbon dioxide, but you will not get rid of "just" dissolved CO₂.

Thanks^
then how can I calculate the solubility of CO2 in such a acid solution?

[fledarmus]

If there is still some residual gas in solution, how to push them away from the solution?

The two most common ways of degassing solutions are to stir them under a vacuum for several minutes, or to bubble an inert gas through them for several minutes. I deal with a lot of oxygen-sensitive reactions, and I usually employ a flush-and-fill approach - stir under vacuum for a couple of minutes, bubble nitrogen through the solution for a couple of minutes, stir under vacuum, bubble nitrogen, repeat until bored.

That won't remove any carbon dioxide bound up as carbonate, but it should remove any free carbon dioxide dissolved in your solution.

[Burian]

If there is still some residual gas in solution, how to push them away from the solution?

The two most common ways of degassing solutions are to stir them under a vacuum for several minutes, or to bubble an inert gas through them for several minutes. I deal with a lot of oxygen-sensitive reactions, and I usually employ a flush-and-fill approach - stir under vacuum for a couple of minutes, bubble nitrogen through the solution for a couple of minutes, stir under vacuum, bubble nitrogen, repeat until bored.

That won't remove any carbon dioxide bound up as carbonate, but it should remove any free carbon dioxide dissolved in your solution.

3X very much!
I'll try your methods^