Consequently salt solutions containing Ca2+ ions are slightly acidic (they contain free H+ ions)
These free H+ ions can react with the carbonate ions in a solution (of hydrogen carbonate ions) releasing CO2 gas - it's an acid - base reaction.
So - if CaCl2
solution is slightly acidic - CO2
should evolve. Not long, as the pH of CaCl2
solution is about 6.76 - not much H+
ions to be used. pH calculated using BATE, so only hydrolysis taken into account, no complex equilibrium - although I suppose it is already accounted for through pKb values.
What about other solutions? Why does CO2
evolve from the solution made by just diluting AS?
Not to mention contradiction - if CaCl2
is acidic, why does CO2
evolve slowest from CaCl2
It doesn't make sense, no matter which way you look at it. There is some puzzle element missing.