Chemistry
Identify the cation [positive ion] and anion [negative ion] in - A, B and C. Also identify P, Q, R, S, T, U, V, W.
(a) Substance 'A' is water soluble and gives a curdy white precipitate 'P' with silver nitrate solution. 'P' is soluble in ammonium hydroxide but insoluble in dil. HNO3. Substance 'A' reacts with ammonium hydroxide solution to give a white precipitate 'Q' soluble in excess of NH4OH.
(b) A solution of substance 'B' is added to barium chloride solution. A white ppt. 'R' is formed, insoluble in dil. HCl or HNO3. A dirty green ppt. 'S' is formed on addition of ammonium hydroxide to a solution of 'B' and the precipitate is insoluble in excess of ammonium hydroxide.
(c) Substance 'C' is a coloured, crystalline salt which on heating decomposes leaving a black residue 'T'. On addition of copper turnings and conc. H2SO4 to 'C' a coloured acidic gas 'U' is evolved on heating. A solution of 'C' is added to NaOH soln. until in excess. A pale blue ppt. 'P' is obtained insoluble in excess of NaOH. A solution of 'C' is then added to NH4OH soln. in excess to give an inky blue solution 'V'. A solution of 'C' is warmed and hydrogen sulphide gas is passed through it. A black ppt. 'W' appears.
Related Questions
The following materials are provided – solutions of cobalt chloride, ammonia, potassium permanganate, lime water, starch-iodide, sodium hydroxide, lead acetate, potassium iodide. Also provided are litmus and filter papers, glowing splinters and glass rods. Using the above how would you distinguish between :
(a) a neutral, acidic and a basic gas
(b) oxygen and hydrogen gas
(c) carbon dioxide and sulphur dioxide gas
(d) chlorine and hydrogen chloride gas
(e) hydrogen sulphide and nitrogen dioxide gas
(f) ammonia and carbon dioxide gas
(g) zinc carbonate and potassium nitrate
(h) hydrated copper sulphate and anhydrous copper sulphate
(i) ammonium sulphate and sodium sulphate.
Give a chemical test to distinguish between the following:
(i) Sodium carbonate and sodium sulphate
(ii) Potassium chloride and potassium nitrate
(iii) Copper carbonate and copper sulphite
(iv) Lead chloride and lead sulphide
(v) Iron (II) sulphate and iron (III) sulphate
(vi) Calcium sulphate and zinc sulphate
(vii) Lead nitrate and zinc nitrate
(viii) Copper sulphate and calcium sulphate
(ix) Manganese dioxide and copper (II) oxide
(x) dil. HCl, dil. HNO3, dil. H2SO4.
[explain the procedure for the preparation of the solutions for the above tests wherever required]
Match the 'cations' A to F and the solubility of ppt. G or H with the correct colours from 'X' and 'Y'.
'X' on addition of NaOH in excess Cation Solubility of ppt. in excess 'Y' on addition of NH4OH in excess Cation Solubility of ppt. in excess 1. Reddish brown ppt. A: Ca2+ G: Soluble 6. Dirty green ppt. A: Ca2+ G: Soluble 2. Pale blue ppt. B: Zn2+ H: Insoluble 7. No ppt. formed B: Zn2+ H: Insoluble 3. Gelatinous white ppt. C: Fe2+ 8. Gelatinous white ppt. C: Fe2+ 4. Chalky white ppt. D: Cu2+ 9. Pale blue ppt. D: Cu2+ 5. Milky white ppt. E: Pb2+ 10. Chalky white ppt. E: Pb2+ F: Fe3+ F: Fe3+ Select the correct 'anion' of a salt from the anions given, which matches with description 1 to 5.
A: CO32-, B: NO31-, C: SO42-, D: Cl-, E: S2-
- The salt soln. reacts with AgNO3 soln. to give a white ppt. insoluble in dil. HNO3.
- The salt soln. reacts with Ba(NO3)2 soln. to give a white ppt. insoluble in dil. HNO3.
- The salt soln. reacts with Ba(NO3)2 soln. to give a white ppt. soluble in dil. HNO3 but insoluble in dil. H2SO4.
- The salt reacts with dil. H2SO4 on heating evolving a gas which turns KMnO4 soln. pink to colourless.
- The salt reacts with conc. H2SO4 on heating evolving a coloured gas which turns potassium iodide paper brown.