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點解cyclohexane, cyclohexene ,methylbenzene 同acidified potassium manganate(VII) react會form左2 layered ge mixture?

Cyclohexane, cyclohexene, methylbenzene are organic solvents. Acidified potassium manganate(VII) is aqueous solution (dissolved in water). When the two liquids are added together, there would be two layers because the organic layer (cyclohexane, cyclohexene or methylbenzene) and the aqueous layer (i.e. water) are not miscible.


methylbenzene同acidified potassium manganate(VII) react form左一層coloureless, 一層brown,brown果層係點形成架?

The methylbenzene is oxidized to benzoic acid by the acidified potassium manganate(VII). When the amount of sulphuric acid is insufficient, the potassium manganate(VII) is reduced to manganese(IV) oxide which is finely divided brown solid. The brown manganese(IV) oxide give a suspension looked brown.
C6H5C H3 + H2SO4 + 2KMnO4 → C6H5C OOH + K2SO4 + 2M nO2 + 2H2O

However, if the amount of sulphuric acid is sufficient, the potassium manganate(VII) would be reduced to manganese(II) sulphate which gives a colourless aqueous solution (as the pink colour of manganese ions is too pale to observe). Hence, two colourless layers would be observed.
5C6H5C H3 + 9H2SO4 + 6KMnO4 → 5C6H5C OOH + 3K2SO4 + 6M nSO4 + 14H2O

2010-07-24 13:55:57 補充：
All the organic solvents (cyclohexane, cyclohexene and methylbenzene) and the organic products (benzoic acid and 1,2-dibromocyclohexane) are colourless. Therefore, the organic layer is colourless.