Reactions between Ca(OH)2 and CO2, and Sr(OH)2 and CO2 So I'm doing an investigation, and it involves using supersaturated solutions of Ca(OH)2 and of Sr(OH)2. I notice that there's always a flaky precipitate formed on top. I need to know about the reactions with carbon dioxide. Is it carbonate that's formed? Or is it hydrogen carbonate? Why?
Your solid is the respective carbonate. Group II bicarbonates can form aqueous solutions, but do not form stable solids, ergo the solid flakes must be carbonate and formed along the lines of:

$$\ce{Ca(OH)2 (aq)+ 2CO2 (aq/g) &lt;=&gt; Ca^2+ + 2(HCO3)- (aq) &lt;=&gt; CaCO3 (s) + CO2 (aq/g)}$$