Investigating the effect of concentration on the rate of reaction between sodium thiosulphate and hydrochloric acid.

Apparatus:

hydrochloric acid, sodium theosulphate, 2 measuring cylinders, 2 pipettes, 1 conical flask, 1 stop clock and a pair of goggles.

Diagram:

Hazards:   Hydrochloric acid- wear goggles

Method:

• First of all we gathered all the apparatus and set it up as in the diagram.
• We drew a cross an a piece of paper and put a comical flask on top
• We then poured 50 cm3 of sodium theosulphate into the conical flask and added 10cm3 of hydrochloric acid and timed how long it took for the cross to disappear.
• We recorded our results and continued thusly, changing the concentration of the hydrochloric acid.
  

Results:  

1st test

2nd test

3rd test

Conclusion:

My conclusion is that, the higher the concentration, the faster the rate of reaction, or the faster the sodium theosulphate will turn yellow and opaque. This matches my prediction.


Evaluation:

I think this experiment went well; there isn’t anything I would change except maybe starting it with higher concentration of acid. There are no anomalous results to note