Why is it useful to a chemist to have this classification system for the types of chemical reactions?
What other classification systems do we see in science, or even in everyday living? How do these systems make our lives easier?
Let's suppose the classification of the five types of chemical reactions did not exist. Would you then be able to predict products of a given chemical reaction? Why or why not?
In chemistry, it makes the job a lot easier if you know what to expect. That's the main reason for having a system of classification, so people who are learning the 'ins and outs" of what works and what doesn't have some kind of set of notes to go by.
Just the other day I had a question from a student who was doing a chemistry lab that involved the use of potassium thiocyanate (KSCN). He kept asking if he had done something wrong, because the instructions told him to observe a color change, and he didn't get a color change. He was reacting potassium thiocyanate with ferric chloride. Now, in the presence of iron ions (Fe +3), the thiocyanate part of the reaction turns a fiery, blood red. Having that instruction and classification alerted the student possibly he had done something wrong.
If the classification system did not exist, someone would probably sit down and start creating one. The human race is predicated upon making intelligent decisions, and making intelligent forecasts beyond those decisions. We rather like saying "If I mix this with that, I'll get that and this". Classification helps put things in their proper place