insoluble salt ..........please help (20 points)

that see you what acid you add.
for example: calcium carbonate can react with dilute hydrochloric acid, as the product calcium chloride is soluble.If you add dilute sulphuric acid, there will be no reaction because a protective(insoluble) layer ---calcium sulphate formed.

acids will react with carbonates to give carbon dioxide although they are insoluble in water. it's because the insoluble carbonates contain carbonate ion that will react with hydrogen ion in the acid. however, some carbonates will not react will some acids, such as calcium carbonate and dilute sulphuric acid. it's because insoluble calcium sulphate will be formed on the surface of calcium carbonate and stop the reaction by acting as protective layer.