Iodine clock reaction
This iodine clock reaction project can apply to the real world in different ways, but I think the biggest way is concentration. After doing some research, I found out that it can teach you about concentration, because it shows you that once you add any bigger amount to a substance, it changes reaction time, or in a real world case, how a substance feels, acts, looks, and possibly how it smells.

I know this is really late and you probably don't need this and you are done your project, but I'm just a bored grade 7 doing the same science project.