Colour tests sim
Each tube holds 2.0 cm³ and each drop is 0.05 cm³.
Colour tests · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Each tube holds 2.0 cm³ and each drop is 0.05 cm³. Oxidising and reducing agents: aqueous potassium iodide (0.10 mol/dm³) turns yellow-brown with an oxidising agent, because the iodide is oxidised to iodine. Acidified potassium manganate(VII) goes from purple to colourless, and acidified potassium dichromate(VI) from orange to green, with a reducing agent. Both are acidified with dilute sulfuric acid. The tubes hold dilute chlorine water (0.001 mol/dm³), an oxidising agent, and sulfur dioxide solution (0.01 mol/dm³) and iron(II) sulfate (0.03 mol/dm³), which are reducing agents. Two oxidising agents, or two reducing agents, do not react. Each drop of manganate(VII) or dichromate(VI) brings 1.0 × 10⁻⁶ mol, and its colour stays from the drop on which the tube's reducing agent is all used up. With iron(II), the solution left is pale yellow, from the iron(III) ions made. Bromine water: shake the hydrocarbon with bromine water in the dark. An alkene decolourises it, from orange-brown to colourless, because bromine adds across the C=C bond. An alkane leaves it orange-brown: hexane and water do not mix, and the bromine moves up into the hexane layer. In ultraviolet light an alkane would react slowly by substitution. Every C=C takes up one Br₂, so oil Q decolourises 25 drops before the colour stays. Colours are worked out from the concentration of each coloured substance in the tube.
- Liquid colours come from each substance's concentration
- Tubes are numbered on the rack
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