Investigating the Effects of Dilution on the Rate of Reaction Between Sodium Thiosulphate and Dilute Hydrochloric Acid

Investigating the Effects of Dilution on the Rate of Reaction Between Sodium Thiosulphate and Dilute Hydrochloric Acid

Aim:

To investigate, the effects of dilution on the rate of reaction

between sodium thiosulphate and dilute hydrochloric acid.

Background information:

The dilution variable does not occur to the hydrochloric acid but it

occurs to the sodium thiosulphate. The reason why it does not occur in

hydrochloric acid is because it needs to be constant and it is already

dilute due to the acid's concentration.

To dilute the sodium thiosulphate, you would need to see the

concentration of the sodium thiosulphate. During each experiment the

concentration will decrease. Distilled water is added to help dilute

the solution. This process makes the sodium thiosulphate react much

slower and in turn makes it go cloudy. This increase in the time

period between each experiment is caused by the collision theory.

"More collisions between molecules increase the reaction"

The following are the main factors affecting the collision theory:

1. Temperature: When the temperature is increased, it increases the

number of collisions as the molecules vibrate more and move around

more as the heat makes the mass expand.

2. Concentration: When the concentration is increased, the

collisions increase because there are more molecules to react.

3. Catalysts: adding the number of catalysts increases the number of

collisions.

4. Size of solid particles: If there is a large particle as a

reactant, it will cause more collisions because the particles

would have a larger area to work on.

The only thing that would probably affect our experiment from the list

above is the aspect of concentration.

The diagrams below show what will happen in the reaction.

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KEY:

- Sodium thiosulphate

- Water

- Hydrochloric acid

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When there are more hydrochloric atoms for the sodium thiosulphate