Question 53
Investigate sodium thiosulfate solution with dilute hydrochloric acid at different temperatures, using 10 cm³ thiosulfate solution and 1 cm³ acid each trial, timing when sulfur precipitate hides a black cross. Carry out a trial run: place 10 cm³ thiosulfate solution in a test tube, clamp it with the cross behind it, add 1 cm³ hydrochloric acid and start timing. Time until the cross is no longer visible; transfer the used solution to the teacher-provided sodium hydrogencarbonate waste container. The source method says to insert a stopper.
