C is a mixture of an organic and an inorganic salt. The test recorded in the table below were performed as indicated,
(a)Copy and complete the table as appropriate.
| Test | Observation | Inference |
| (i) C + water mixed thoroughly and filtered | Partially soluble, colourless filtrate, white residue | |
|
(ii) Portion of filtrate from (i) + NH\(_{3(aq)}\) in drops, then in excess |
White precipitate which dissolves in excess to give a colourless solution | |
| (iii) Portion of filtrate from (i) + NH\(_3\) in drops, then in excess | White precipitate insoluble in excess | |
| (iv) Portion of filtrate from (i) + conc. HCl + heat | White precipitate which dissolves on warming and reappears on cooling | |
| (v) Portion of filtrate from (i) + conc. H\(_2\)SO\(_4\) + gentle warming | Brown fumes produced on warming | |
| (vi) Residue from (i) + iodine solution | Blue-black colouration | |
| (vii) Residue from (i) + Fehling's solution + heat | ||
| (vii) Residue from (i) + dil HCl solution + heat + Fehling's solution |
(b) From the information provided and your inference, identify the compounds of C
(c) Describe the action of heat on a solid sample of the inorganic component Write an equation for the reaction.
(d) State what would be observed if an aqueous suspension of the organic component were heated to boiling
| Test | Observation | Inference |
| (i) C + water mixed thoroughly and filtered | Partially soluble, colourless filtrate, white residue | One soluble and the other is not |
|
(ii) Portion of filtrate from (i) + NH\(_{3(aq)}\) in drops, then in excess |
White precipitate which dissolves in excess to give a colourless solution | Zn\(^{2+}\), pb\(^{2+}\) or Al\(^{3+}\) present |
| (iii) Portion of filtrate from (i) _ NH\(_3\) in drops, then in excess | White precipitate insoluble in excess | Pb\(^{2+}\) or Al\(^{3+}\) present |
| (iv) Portion of filtrate from (i) + conc. HCl + heat | White precipitate which dissolves on warming and reappears on cooling | Pb\(^{2+}\) confirmed |
| (v) Portion of filtrate from (i) + conc. H\(_2\)SO\(_4\) + gentle warming | Brown fumes produced on warming |
fumes of NO\(_2\); NO\(_3\) + present |
| (vi) Residue from (i) + iodine solution | Blue-black colouration |
Residue is starch |
| (vii) Residue from (i) + Fehling's solution + heat | No precipitate or any visible reaction |
Starch is non-reducing or reducing sugar absent |
| (vii) Residue from (i) + dil HCl solution + heat + Fehling's solution | Brick - red precipitate | Starch has been hydrolysed to reducing sugar |
(b) C is a mixture and lead II trioxonitrate (V) is one
(c) The precipitate (makes a cracking sound) produced copious brown fumes of Nitrogen (IV) oxide on heating. The residue turns red when hot and yellow when cold, lead (II) oxide and a gas that relights a glowing splint evolved. Pb(NO\(_3\))\(_2\) \(\to\) PbO + 2NO\(_2\) + O\(_2\)
(d) It will give a colloidal solution (or jelly-like solution)
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