Iodine time clock reaction
This can be the hydrogen peroxide/ potassium iodide ‘clock' reaction. A solution of hydrogen peroxide is combined with one containing potassium iodide, starch and sodium thiosulfate. After a few seconds the colourless mixture all of a sudden turns darker blue. This really is one of many reactions usually called the iodine clock. It can be used while an introduction to experiments in rates / kinetics.
This demo can be used by secondary level as an introduction to some in the ideas about kinetics. It can be used to stimulate discussion with what factors impact the rate of reaction. Playing also makes a useful starting-point for a student investigation. Because described this is intended like a demonstration, best done on a mass for the most visual impact. The demonstration alone takes less than 1 small. For a scholar investigation, the quantities essential would be small but amounts then need to be measured quite accurately with, for example , non reusable plastic syringes. It also results in a class competition aiming for a change at a teacher identified time.
Equipment and chemicals
Eye safety Balance (1 or 2 d. p. ) Volumetric flasks (1 dm3), Beakers (100 cm3), 5 Beaker (250 cm3) Beaker (2 dm3) Hot tubes, a few Boiling tube rack Measuring cylinder (50 cm3) Measuring cylinders (100 cm3), 2 Stirring fishing rod or magnetic stirrer and follower (optional) Stopclock/timer, 5 0. 2 g soluble starch 1M sulfuric acid (Irritant), 60 cm3 Potassium iodide (KI), 6. 0 g. (Low hazard) Sodium thiosulfate-5-water (Na2S2O3. 5H2O), six. 5 g (Low hazard) 20 volume level hydrogen peroxide solution (H2O2(aq)), 100 cm3 (Irritant) Deionised/distilled water, one particular dm3.
20 volume hydrogen peroxide is usually Irritant. Consider CLEAPSS® Hazcard 50. 1M sulfuric acidity is Corrosive. Refer to CLEAPSS® Hazcard 98A 1 Remedy X plus the starch answer should be constructed before the exhibition. The alternatives will keep overnight, but best...