whats a base that reacts with hydrochloric acid that has a ratio of 2:1 like water?

Answer 1

How about Ca(OH)2 -- calcium hydroxide.

Also Magnesium hydroxide, or barium hydroxide, or strontium hydroxide. Really any of the alkaline earths, because they'll always go to a valence of +2.

There are a lot of the transition metal hydroxides that would fit the bill, too, but many of those are insoluble.

Answer 2

I am not so used in identifying elements and compounds but I am good at chemical reactions. Ok lets take Calcium carbonate as the mystery carbonate. When Calcium carbonate reacts with HCl here's the reaction. CaCO3 + Hcl -----> CaCl2 + H2O + CO2 CaCl2 is soluble and hence wont appear as precipitate CO2 will liberate so you're left with CaCl2 + H20 Now if you add NaCO3 to this solution, little bits of white powder appears. Which means the solution contains calcium chloride which means the carbonate given is of calcium. Similarly if you it is barium carbonate. You will finally be having BaCl2 + H20 So now if you add H2SO4 to this solution you will be having BaSo4 which is a white precipitate which means it is barium carbonate. Like this you can identify the other carbonates too