Required practical - Investigate the rate of reaction by colour change

Question 1

Method to required practical

Answer 1

1) Using a measuring cylinder, add 50 cm3 of dilute sodium thiosulfate solution to a conical flask.
2) Place the conical flask on a piece of paper with a black cross drawn on it.
3) Using a different measuring cylinder, add 10 cm3 of dilute hydrochloric acid to the conical flask. Immediately swirl the flask to mix its contents, and start a stop clock.
4) Look down through the reaction mixture. When the cross can no longer be seen, record the time on the stop clock.
5) Measure and record the temperature of the reaction mixture.
6) Repeat steps 1 to 5 with different starting temperatures of sodium thiosulfate solution.