How does concentration affect the time a reaction takes to complete?

How does concentration affect the time a

reaction takes to complete?

Introduction

I am going to do an experiment to find out how the concentration of a base affects its reaction time with an acid. In this experiment, the base will be sodium thiosulphate, and the acid will be hydrochloric acid.

Prediction

I predict that as I use less and less sodium thiosulphate in my solution the reaction will take longer to happen.

Reason

I have based my prediction on the collision theory. The collision theory says that as particles collide, a chemical reaction takes place and as there are less and less particles they don’t collide as often so the reaction takes longer. This can also be affected by heat, as the heat increases the particles become more excited and so collide more.

I have applied this theory to my experiment because the reaction is taking place by collision and I am using less and less particles for each reading and so making the reaction take longer.

Method

I will begin by setting up my equipment, I will need a measuring cylinder, and a flask. I will keep the concentration of hydrochloric acid the same throughout the experiment and change the amount of sodium thiosulphate, this means I will only get one variable. The total volume of the solution will remain 55cm cubed throughout the experiment. I will achieve this by ...