Inorganic analysis

1919 The Analyst  
titrating sodium aluminate with hydrochlorio acid, using phenolphthaltun as indicator, the following reaction takes plaoe : AI,(ONa),+ 3HC1= Al(OH), + 3NaC1, whilst on titrating aluminium hydroxide, using methyl orange as indicator, the reaotion is : In titrating orude alkalis oontaining only negligible amounts of dumina, methyl orange may be used as indicator, but should any material proportion of aluminium be present, the alkaline solution is boiled for five minutes with a slight excess (1 to
more » ... slight excess (1 to 2 c.c.) of :-mid, in presence of phenolphthalein, cooled to the ordinary temperature, and titrated btwk with %alkali. In titrating sodium hydroxide in sodium aluminate, Lunge's method (Z&tsch,. imgew. Chsm., 1890,227, 293) may be used, aocording to whioh the aample is diHsolved in water and an aliquot portion titrated with + hydroohlorio acid in preeenoe of phenolphthalein. But if, as directed, the titration is effected in the boiling liquid as a safeguard against carbon dioxide, the results will be too low. For example, 10 C.C. of a solution oontaining 0-2 grm. of sodium aluminate required 10.2 C.C. of 9 hydrochlorio aoid at boiling-point, and 11-1 ~o . at the ordinary temperature. It is therefore necessary to titrate the boiling liquid until colourIess, then to 0001 the flask rapidly in a ourrent of oold water, md to complete the fitration of the oold liquid. AXOH), + 3HCl= AQ + 3Hs0.
doi:10.1039/an9194400351 fatcat:s5hkn2zchve3tlgjmhx4xjci4a