Aim
To study the effect that temperature and concentration of iodide ion solution have on the rate of iodide ion I⁻ oxidation by peroxodisulphate ion S₂O₈⁻, creating an iodine clock reaction.
Introduction
I decided to choose as the topic for my investigation the rate of reaction for its vital importance in the human body. Indeed I am really interested in Biology and especially physiology and I would like to study medicine. The rate at which different reactions happens in the human body is very important for it to correctly work. Reactions in the body are affected by the concentration of the reactants, but also by the temperature: fever …show more content…
Even if at the beginning nothing would seem to be happening, after a certain amount of time the observer should be able to observe a sudden change in the colour of solution: from colourless to blue-black. Measuring this time it is possible to find the rate of reaction, reciprocal of the time. The chemical reaction taking place is a redox reaction where iodide ion is oxidized and peroxodisulphate ion is reduced. This is the full ionic …show more content…
Volume of sodium thiosulphate Na2S2O3 solution used
It will be kept fixed at 2 cm3 throughout the experiment.
Volume of starch solution used
It will be kept fixed at 5 drops throughout the experiment.
Volume of iodide I- solution used
It will be kept fixed at 10cm3 throughout the experiment. Volume and concentration are related by the equation n=MV/100 where M is the concentration, V the volume and n is amount of solute.
Given that the varying variable is the concentration is the iodide solution, the volume of iodide solution must be kept constant.
Apparatus/ Materials
Pipette (25.00±0.03 cm3), pipette (10.00±0.02 cm3), pipette (5.00±0.001 cm3), burette (50.00±0.05 cm3), micropipette (1.00±0.003 cm3), digital stop watch (±0.01s ???), test tubes, beakers, test tube rack, volumetric flask, , retort stand with clamp, distilled water, pipette filler, spatula, dropper, water bath, thermometer , standard potassium iodide KI 1.0 mol dm-3 solution, sodium thiosulphate Na2S2O3 0.05 mol dm-3 solution, sodium peroxodisulphate Na2S2O8 0.04 mol dm-3 solution and starch solution
Experimental procedures Preparation of chemical