How does dilution affect the reaction rate?
The more the solution of a reactant is diluted, the slower the reaction will occur.
The key thing you need to understand here is that chemical reactions depend on reactant particles bumping into each other (collision theory).
The more concentrated a reactant is, the more likely it will be to bump into other reactants and product chemical change.
Here is video of a quick lab performed to test this. In the video, varying concentrations of
video from: Noel Pauller
Hope this helps!