Titanous chloride test

M.I. Fauth H. Stalcup, AnalChem 30,1670— 72(1958) Be CA 53, 2929(1959) [Evaluation of six methods for detn of nitrogen in NGu. (Nitro N methods tested are modified nitrometer — greatest precision of the six acetate-buffered titanous chloride transnitration with sulfuric acid and Bowman-Scott). Total N methods are modified Kjeldahl and micro-Dumas — better of these two. The titanous chloride and trans-nitration methods are satisfactory]... 

Nitrogen Content is determined by titanous chloride method as described below. Before proceeding with the test, it is necessary to prepare the following reagents ... 

Nitrogen Content is detd by Titanous Chloride Method in the same manner as described under Basic Lead Styphnate, Test 10... 

If complete saponification is achieved, remove the rubber stopper from the inlet tube of the flask and attach a source of inert gas (nitrogen or carbon dioxide) to the tube. After allowing t "ip gac rrt flow for 3 mins stiti (whils cooninuin the flow of gas until, the end of test) in 2-ml increments 40ml of the 0.2N titanous chloride soln, swirling the flask after each addn. Then swirl the flask for another 15 secs and add 25ml of 15% HC1 soln, followed by 5ml of 20% ammonium thiocyanate soln... 

Transfer the soln to a vol flask, take an aliquot and test it colorimetrically Note If additional identification is desired, det nitrogen content by titanous chloride... 

Test an acidified solution of hydroxylamine hydrochloride with an aqueous solution of mercuric chloride, and also with a solution of titanous chloride if available. Write equations for the reactions. 

A) Oxidation states of transition elements. In four large test tubes place about 20 ml of dilute solutions of titanic chloride, ammonium metavanadate, potassium dichromate, and ammonium molybdate. Add to each about 10 ml of concentrated hydrochloric acid and several grams of granulated or mossy zinc. Set under the draft. Note all the color changes and interpret them by means of ionic equations. 

Procedure. One drop of the test solution, which may be neutral or 0.1 AT with respect to hydrochloric acid, and which must be free from interfering substances, is mixed on a spot plate with a microdrop of 1 % titanous chloride solution and a microdrop of a 0.005% water solution of malachite green. Depending on the concentration of tungsten, the solution becomes colorless (very pale violet) more or less rapidly. With small quantities of tungsten, it is well to make a blank test. 

Requirements and tests for Pyroxylin type NC are described in Specs listed here as Refs 51 52 and for Technical NC(for use in organic coatings) in Ref 53. Several US std tests are described in Ref 55. In Ref 49 is described detn of N content of NC by IR spectrophotometry and in Ref 55 detn of NC by chromous chloride reduction. One of the latest methods on detn of N content in NC by ferrous-titanous titration is described in Ref 44. This test will be included in the next edition of US Military Standard Spec... 

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