Factors that affect the rate at which Sodium Thiosulfate (Na2S2O3) reacts with Hydrochloric Acid (HCl)

I am to investigate the factors that affect the rate at which Sodium

Thiosulfate (Na2S2O3) reacts with Hydrochloric Acid (HCl).

When sodium thiosulfate is mixed with hydrochloric acid, a reaction

takes place, leading to a precipitate of sulphur being formed. This

turns the solution cloudy. I shall use this clouding to investigate a

factor that affects the rate of reaction, the factor being

temperature.

To do this, I shall react Sodium Thiosulfate with Hydrochloric Acid at

a range of temperatures, between 20°C and 40°C, at 5°C intervals,

leading to 5 results. The experiment shall be carried out twice, to

give accuracy, and allowing me to check for agreement between results.

I predict that as the temperature that the reaction takes place at

increases, the less time it will take for the reaction to take place

and for the solution to cloud. My prediction is based on the collision

theory, which says that

· Reacting species must hit together

· Species must hit together with more than the activation energy

needed

Increasing the temperature of the atoms taking part makes them move

more and faster, enabling more collisions to take place, speeding up

the reaction. The added heat energy also allows more collisions to

have the required activation energy, again, speeding up the reaction.

In order to make this experiment a fair test, I changed only one input

variable, the temperature. I kept the amount and concentration of the

liquids the same (20m...