How does changing the concentration affect the rate of reaction?

Investigating the Effect of Concentration on Reaction Rate

Aim:
I want to investigate how concentration effects the reaction rate.

Equipment:
Conical Flask
Beaker
Measuring Cylinder
Stopwatch
Paper with a black cross "X"
0.1mol/L Sodium Thiosulfate
2.0mol/L Hydrochloric Acid

Method:

1. Put the piece of paper with the X on the bench and put the conical flask on it.
   
2. Measure 10mL of Sodium Thiosulfate and put it into the conical flask.
   
3. Measure 40mL of Water and put it into the conical flask. Swirl to mix.
4. Measure 5mL of HCl.
5. Pour the HCl into the conical flask, start the timer and swirl the flask.
6. Stop timing when the you can't see the cross on the paper.
   
7. Wash out the flask thoroughly.
8. Repeat experiment 20mL of Sodium Thiosulfate and 30mL of Water.
9. Repeat experiment 30mL of Sodium Thiosulfate and 20mL of Water.
10. Repeat experiment 40mL of Sodium Thiosulfate and 10mL of Water.
11. Repeat experiment 50mL of Sodium Thiosulfate and no Water.

Results:
10mL Thiosulfate/40mL Water took 239sec for the X to disappear.
20mL Thiosulfate/30mL Water took 119sec for the X to disappear.
30mL Thiosulfate/20mL Water took 64sec for the X to disappear.
40mL Thiosulfate/10mL Water took 45sec for the X to disappear.
50mL Thiosulfate/0mL Water took 32sec for the X to disappear.

Analysis:

Conclusion:
A chemical reaction is when two reactant particles collide.
They must collide with enough force and in the correct orientation.
As I increased the concentration of the reactants, there were more reactant particles that were able to react. The more particles, the higher the chance of a successful collision.
This means the rate of reaction will increase.