Dissapearing cross experiment

Question 1

method

Answer 1

1) Measure 10 cm3 of 0.2 mol dm-3 hydrochloric acid and 10 cm3 of sodium thiosulfate in separate clean measuring cylinders

2) Put the solutions in separate boiling tubes

3) Choose a temperature to investigate use water bath to get the two solutions to that temperature by
placing the boiling tubes in the water bath

4) Place the flask on the centre of the large cross; first add the sodium thiosulfate to the flask

5) Then add the
hydrochloric acid and start the stopwatch and swirl to mix the solutions.

6) Stop the clock when the cross disappears and note the time.

7) Repeat the experiment for four more different temperature