Notes on qualitative analysis.

  • Fenton, Henry John Horstman, 1854-1929.
Date:
1906
Catalogue details

Licence: In copyright

Credit: Notes on qualitative analysis. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    Nitrites {contimied). Potassium iodide, in presence of dilute HCl or HjSO^, liberation of iodine (detected by starch-paste or CSg), 2KN0j + 2KI + 4HC1 = 4KC1 + 2B.^0 + 2N0 + I,,. Urea, added to free nitrous acid (or a nitrite + dilute HaSO^), gives oflF nitrogen and carbon dioxide, CO(NH2)3 + 2HN0, = COj + 3HjO + 2Na (complete on heating). Boiled with zinc and caustic soda they behave like nitrates, ammonia being evolved. Silver nitrate, white ppt. of silver nitrite, soluble in hot water. Potassium permanganate, in preBence of dilnte HjS04, is at once discolorized. Meta-diamino-benzene CjH4(NHj)g in presence of dilute H2SO4, a yellow colour, even in very dilute solutions. Aniline sulphate (one or two drops of solution) triturated with a concentrated solution of a nitrite gives the odour of phenol CgHjOH. If quite free from nitrates, it is stated that nitrites when mixed with concentrated HgSO^ ^so to form nitrosyl-sulphuric acid) do not give a red colour with brucine; this is true if certain conditions are fulfilled. ACETATES. {■E.g. CHj.COONa.) Heated with concentrated HjSOi, acetic acid is given off (recog- nized by its odour), CH3. COONa + H2SO4 = NaHSO, + CH,. COOH. Heated with concentrated H3SO4 and alcohol (one or two drops) the characteristic odour of ethyl acetate is produced, CH,. COOH + (C2H5)OH = CH3. COO(CsHb) + H^O. Heated with arsenious anhydride, characteristic (poisonous) odour of cacodyl oxide As2(CH3)40 is produced. Neutral solutions of acetates give with Ferric chloride, a red colour, due to ferric acetate Fe(CH3C02),. On boiling the solution, a brown ppt. is produced of basic ferric acetate Fe(CH8C02)3a3Fe(0H)3. The red colour is bleached by HCl but not by HgClg. Silver nitrate gives, in strong solutions, white ppt. of silver acetate, soluble in hot water.