If it is middle school chemistry, there are some rules to judge whether there is a reaction between substances. For example, strong acids and strong bases produce weak acids and weak bases, so that they can react. On the contrary, weak acid and weak base can not produce strong acid and strong base. It can also be judged by the relative redox intensity, which is also weak in compulsion. But whether a specific substance can react depends on whether there is such a reaction in fact, and these laws cannot be used to fabricate non-existent reactions. In addition, in the middle school stage, we should remember more reactions and do more questions to judge whether it is ok or not.

The metathesis reaction gives you a group of substances. You should combine the anion and cation to see if there are any insoluble substances, volatile substances and hard-to-ionize substances (such as H2O). If there are, you can react. Otherwise you won't be able to react. (There is a problem with ion * * *) The redox reaction gives you a group of substances. You must first judge whether there are oxidants and reductants in the two substances. If you are given substances A and, you can react, otherwise, basic oxides can react with acids, and acidic oxides can react with bases. Organic chemistry, just remember the reaction equations mentioned in the book.