Wednesday, 3 August 2011

X marks the spot

The theory topic for chemistry today was electrolytic cells electrolytic cells, fuel cells and secondary cells. 

Today students learnt how to design an investigation. To practise their manipulative skills students performed a formative practical on the effect of concentration on
reaction rate. The academy chemistry students varied the concentration of thiosulphate. 


Setting up practical
When hydrocholoric acid was added to the sodium thiosulphate solution, a pale yellow precipitate of sulphur formed.
As the concentration of the sodium thiosulphate solution decreased, the time taken for the precipitate to form takes longer and longer.
  
X was written on white piece of paper and placed under the conical flask. The students recorded the time it took for the X to disappear using a stop watch.


X marks spot

Adding thiosulphate
Adding hydrochloric acid


See the X

X disappears
Sulphur precipitate forms

Recording reaction time



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