K-4 sentence example

k-4
  • Rossler and Hasslacher prepare the double potassium sodium cyanide by fusing potassium ferrocyanide with sodium, the product of fusion being extracted with water and the solution evaporated: K 4 Fe(NC) 6 +2Na = Fe+ 4KNC 2NaNC. This process gives a product free from cyanate, which was always formed in the older fusion processes.
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  • Potassium ferrocyanide, K 4 Fe(NC) 6, (yellow prussiate of potash), was first obtained by decomposing Prussian blue with caustic potash: Fe4[Fe(NC)6]3 + 12KHO = 3K 4 Fe(NC) 6 +4Fe(OH) 3; it may be also obtained by warming a solution of ferrous sulphate with an excess of potassium cyanide: FeS04-I-6KNC = K4Fe(NC)6+ K2S04.
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  • Cyanogen compounds of chromium, analogous to those of iron, have been prepared; thus potassium chromocyanide, K 4 Cr(CN) 6.2H 2 0, is formed from potassium cyanide and chromous acetate; on exposure to air it is converted into the chromicyanide, K 3 Cr(CN) 6, which can also be prepared by adding chromic acetate solution to boiling potassium cyanide solution.
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  • It may also be prepared by heating formic and oxalic acids (or their salts) with concentrated sulphuric acid (in the case of oxalic acid, an equal volume of carbon dioxide is produced); and by heating potassium ferrocyanide with a large excess of concentrated sulphuric acid, K 4 Fe(CN) 6 -i-6H2S04+6H20=2K2S04+FeS04+3(NH4)2S04+6C0.
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  • When fused with potassium carbonate it yields potassium cyanide; warmed with dilute sulphuric acid it yields hydrocyanic acid, but with concentrated sulphuric acid it yields carbon monoxide: 6H 2 O + K 4 Fe(NC) 6 + 6H 2 SO 4 = 2K 2 SO 4 + FeSO 4 + 3(NH4)2S04 + 6C0.
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