Methyl orange as indicator

Hydrazine hydrate may be titrated with standard acid using methyl orange as indicator or, alternatively, against standard iodine solution with starch as indicator. In the latter case about 0-1 g., accurately weighed, of the hydrazine hydrate solution is diluted with about 100 ml. of water, 2-3 drops of starch indicator added, and immediately before titration 6 g. of sodium bicarbonate are introduced. Rapid titration with iodine gives a satisfactory end point. 

Determine the methylamine content of the commercial solution by titration with standard acid using methyl orange as indicator. Adjust the quantity of methyl-amine solution in accordance with the methylamine content for some commercial samples, the figure may be 33-40 per cent. 

After the apparatus has been fitted together the caustic soda solution is run in slowly and the flask shaken. The liquid is no more ammonia is evolved be ascertained by testing a drop litmus paper. If the operation is titrated with half-normal sodium methyl orange as indicator. 

Commercial samples of water are frequently alkaline due to the presence of hydrogencarbonates, carbonates, or hydroxides. The alkalinity is determined by titrating a 100.0 mL sample with 0.02M hydrochloric acid using screened methyl orange as indicator (or to a pH of 3.8). To obtain the total cation content in terms of CaC03, the total methyl orange alkalinity is added to the EMA. 

The 42 per cent hydrazine hydrate solution supplied by the Eastman Kodak Company is too dilute for use as such, but may be concentrated by distillation with xylene.1 A mixture of r44 cc. (150 g.) of the 42 per cent solution and 230 cc. of xylene is distilled from a 500-cc. flask through a 17-cm. Hempel column fitted into a cork covered with tin foil. After distillation of the xylene, with about 85 cc. of water, the residue yields on distillation 45-50 g. of 80-85 per cent hydrazine hydrate. This material, assayed best by titration with standard acid using methyl orange as indicator, may be used as such or concentrated further (see Note 6). 

A manual titrimetric method using methyl orange as indicator and sodium tetraphenylboron as titrant has been described [273]. Dodecyl sulfate at concentrations of approximately 10"5 M have been analyzed by a visual two-phase titration in the presence of dichloroethane and tetrabromophenolphthalein ethyl ester [274]. 

Berka et al [59] described an accurate and reproducible coulometric method, with chlorine electrogenerated at the anode, for the determination of micro quantities of primaquine phosphate. Titration was carried out in an anode compartment with a supporting electrolyte of 0.5 M sulfuric acid-0.2 M sodium chloride and methyl orange as indicator. One coulomb was equivalent to 1.18 mg of primaquine phosphate. The coefficients of variation for 0.02-0.5 mg of primaquine phosphate were 1-5%. Excipients did not interfere. 

The determination of nitrogen in the pure product was performed by the usual method of slow distillation with excess of dilute sodium hydroxide solution, the evolved ammonia being collected, during 4 hr. distillation, in standard acid, and determined by titration as usual, with methyl orange as indicator. The yield of ammonia corresponded to 18-19 per cent of nitrogen in this sample. Calculated for FCH2CONH, N= 18-18 per cent. The standard fiuoroacetamide was therefore 100 per cent pure. 

It is also possible with sulphurous acid solutions, using methyl orange as indicator, to titrate with a standard solution of an alkali to the halfway bisulphite stage.6 If necessary the alkali hydrogen sulphite may then be estimated by the addition of mercuric chloride and further titration with alkali, as already described. By this double titration method it is possible to estimate sulphurous aeid in the presence of other sulphur acids.7... 

Quantitative Determination. — Dilute 5 gm. of hydriodic acid with 50 cc. of water and titrate with normal potassium hydroxide solution, using methyl orange as indicator. At least 17 cc. of the normal alkali solution must be required to effect the change in color. 

Quantitative Determination. I lilutr ft >011. oF hvilruhroniir acid wit.li Tit) cc. of wider, mill titrate with normal j itms.-hi 1 nl hydroxide xolnliuii, using methyl orange as indicator. At least. 2-l.( > re. oF the normal alkali solntioii should be requirol to elTcct the rh. iugc ill color. 

Nitrogen. — Dissolve 10 gm. of reduced iron in a mixture of 20 cc. of concentrated sulphuric acid (sp. gr. 1.84) and 200 cc. of water, with the aid of heat. Allow to cool, and when cold add 100 cc. of sodium hydroxide solution (sp. gr. 1.3), and distil off about 50 cc., collecting the distillate in a receiver containing about 20 cc. of water and 2 to 3 cc. of decinormal hydrochloric acid. Titrate the distillate with decinormal potassium hydroxide, using methyl orange as indicator. The ammonia should not have neutralized more than 0.2 cc. of the acid. 

Quantitative Determination. On titrating 1 gin. of potassium bicarbonate with normal hydrochloric acid, using methyl orange as indicator. K) cc. of acid should be required. 

Rubidium Dihydrogen Orthoarsenate, RbH2As04, is obtained in the anhydrous form by fusing together equal parts of arsenious oxide and rubidium nitrate, or by neutralising rubidium carbonate solution with arsenic acid using methyl orange as indicator in the former method it yields tabular crystals and in the latter silky needles. At a dull red heat it forms the metarsenate. 

Analysis of a Mixed Acid.—1. Total Aridity (calculated as H2S04).— About 5 c.cs. of mixed acid are put into a tared weighing bottle and its weight found. This is then washed into a beaker and titrated with N/l caustic soda solution, using methyl orange as indicator. 

E. Blanc calculated for the ionization of constants of phosphorous acid Ki=0 05, and isT2—2 4 XlO-5. I. M. Kolthoff found that the first ionization constant Ky increases from 0 016 in 0 001 Jkf-soln. to 0 062 in O lJf-soln. and the second ionization constant K2, calculated from the H -ion cone, of mixtures of a secondary phosphite with hydrochloric acid is O O07 at 18°. The first stage of phosphorous acid titration may be conducted with methyl-orange as indicator using a comparison soln. with ps—Z 85. A sharp end-point for the second stage is obtained with thymolphthalein as indicator. For the anodic oxidation of the phosphites, vide infra, perphosphates. P. Pascal studied the magnetic properties. 

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