Carbonate can react with hydrochloric acid to produce carbon dioxide, which can be used to test cobalt ions.

CO？ The following 3- (cobalt ion) is not "cobalt ion", but should be called carbonate ion.

The simplest method is to put an appropriate amount of soda ash (or broken marble) in the conical flask, then inject an appropriate amount of dilute hydrochloric acid, and then put a glass sheet coated with clear limewater above the bottle mouth. It is found that the clarified limewater becomes turbid, indicating that soda ash (or broken marble) contains carbonate ions.

The inspection method of ceramics or glass sheets is the same as above, but the phenomenon is that there is no obvious phenomenon in the lime water, indicating that there is no carbonate ion in it.