Chemistry · Oct / Nov 2020 · Paper 61 · Question 3
0620
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The question as text
Solid Y and solid Z were analysed. Tests were done on each solid. tests on solid Y observations Solid Y was dissolved in distilled water to form solution Y. Solution Y was divided into four portions in four boiling tubes. test 1 Aqueous ammonia was added dropwise and then in excess to the first portion of solution Y. a white precipitate formed which was insoluble in excess test 2 Aqueous sodium hydroxide was added dropwise and then in excess to the second portion of solution Y. a white precipitate formed which dissolved in excess to form a colourless solution test 3 A piece of aluminium foil was added to the solution formed in test 2. The mixture was warmed and any gas given off was tested. the gas turned damp red litmus paper blue test 4 About 1 cm3 of dilute nitric acid and a few drops of aqueous silver nitrate were added to the third portion of solution Y. the solution remained colourless, no precipitate formed
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3(a)[1]
ammonia
3(b)[2]
aluminium / Al 3+
nitrate / NO3–
3(c)[1]
(weakly) acidic
Tests on solid Z
3(d)[2]
green precipitate
precipitate insoluble / remains / no further change
3(e)[1]
no change
3(f)[1]
no change / remains purple
3(g)[1]
white precipitate
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