The collision theory of chemical kinetics can be thought of as analogous to a junior high dance. The molecules of A and B can be thought of as guys and girls, and the gymnasium as the closed system. A reaction between molecules can be thought of as when two kids dance.
The first determinant of reaction rate is relative concentrations. When there are few kids total, they are unlikely to just start dancing. However if there are, for example, a lot of boys and few girls, the boys will realize that even if they don.t want to dance right now, they're going to have to get a girl soon before they run out. The contrary situation is also true. And if there are larger numbers of both boys and girls, it is easier for the group to get over that initial reluctance to start dancing, or activation energy.
Another determinant of reaction rate is temperature. The hotter A and/or B get, the more likely it is that reactions will occur. If there's a hot boy, the girls are more likely to dance with him. And the boys are more likely to dance with a hot girl.
A third determinant of reaction rate is a catalyst. Junior high dances are often chaperoned by high school cheerleaders. If these catalysts see that there are not many reactions going on, they will go out and see to it that more reactions occur. Conversely, the presence of teachers and adult chaperones - inhibitors - will very likely slow down the rate at which reactions occur.
Junior high dances also exhibit half-lives. Many junior highers have strict parents, who will pick the kids up after they have reacted, long before the dance is over. The parents will keep coming at a slower and slower rate. Finally, the kids whose parents don't care or even seem to exist will go out after the dance and continue to react slowly until school starts the next day.
Some reactions can be straightforward, but others require intermediate steps and thus reaction rates. For example, the two junior highers who will eventually dance are Brendan and Jenny. However, Brendan is afraid to ask Jenny to dance. Jenny.s friend Angela then takes the initiative to talk to Brendan and tell him that Jenny wants to dance with her. Only after Brendan and Angela have talked will Brendan be able to react with Jenny.
Not all dances react to 100% completion. A number of junior highers will go and react. Not every junior higher will be sold on the concept of dancing with (gasp!) a person of the opposite sex, and a few will retreat to their original side.
This analogy finally breaks down with regards to spatial orientation. In chemistry, both molecules have to be facing each other. But with today.s modern music and the concept of grinding, there can be a whole bucket of reactions without the reactants facing each other. On a final note, all stoichiometries must balance with integral coefficients, because it.s hard for that poor 1/2 kid to get any reactions at all.