New Qualitative Tests for Sulfide and Carbonate

At the present time, the test for sulfide is often made by placing a portion of the sample in an acid solution and identifying the gas evolved either by its odor or by holding a piece of moistened lead acetate paper in the evolved gas. The test for carbonate is often made in a similar war, except for the fact that a drop of barium hydroxide solution is used to identify the gas that is evolved. Both of these tests become increasingly uncertain as the size of the sample being tested is made smaller and smaller, which is the case in semimicro qualitative analysis. This paper describes a test that will detect 0.0001 g. or less, of sulfide ion in 1 ml. of solution, and also a test that will detect 0.001 g. or less, of carbonate ion in 1 ml. of solution

The Use of Semimicro Apparatus in the First Semester of Freshman Chemistry

For many years, many colleges have been using semi-micro qualitative analysis as the laboratory work of the second semester of freshman chemistry while classical experiments that used standard sized apparatus were used during the first semester. Such a plan has the following disadvantages: each student requires two different sets of apparatus during the freshman year, refitting student lockers at mid-year is an arduous task, the expenses of providing two different sets of apparatus for each student is considerable

Vapor Pressure of Iodine Monochloride

The Pearce and Snow dynamic method of measuring vapor pressure has been adapted to the measurement of the vapor pressure of iodine monochloride in the solid and liquid phases. Heats of sublimation, vaporization and fusion were obtained by application of the Clausius-Clapeyron equation

Dissociation Pressure of Some Potassium Polyhalides

Potassium dichloro iodide (KLCL2 or KCL-ICL, m. p. 195°) and potassium trichloro di-iodide (KCL.21CL, m. p. 45°) have been prepared and their dissociation pressures measured

The Solubility of Ignited Ferric and Chromic Oxides

In the gravimetric determination of iron the metal is frequently precipitated as the hydroxide by ammonia. It is then collected by filtration, dried, ignited and weighed as the oxide. Such precipitates when wet, as hydroxides, dissolve instantaneously in acids. After the precipitate has been ignited it often becomes practically insoluble. Such ignition gives a range of temperature of 600° - l000°C, depending on the type of heating device used. Kolthoff and Sandell suggest the fusion of this ignited ammonia precipitate with alkali pyrosulfate in order to convert the oxides into sulfate which then can be dissolved. This procedure is troublesome because the alkali must then be removed before the iron is determined either volumetrically or gravimetrically. Chromium is not usually determined in this way because the strong heating forms some Cr2(CrO4)3 which gives high results unless the oxide is ignited in hydrogen

Qualitative Analysis without Hydrogen Sulfide

A system of Qualitative Analysis is presented in which ammonium sulfide instead of hydrogen sulfide is used as a source of sulfide ion

Some Reactions in Liquid Sulfur Dioxide

Experiments by the authors support the following observations. l. Reactions in liquid sulfur dioxide are usually solvolytic in the sense that the solvent participates in the reactions. 2. Liquid sulfur dioxide under atmospheric pressure does not appreciably react with chlorine save in the presence of a catalyst. 3. Thionyl chloride and sodium sulfite do not react as indicated in the following equation:. SOCl2 + Na2SO3 =NaCl+ 2 SO24. Iodine monochloride and potassium thiocyanate react to form the products indicated in the following equation: 3 KCNS + 3 ICl + 2 SO2 = 3 KCl + I2 + I(CNS)3.2SO2. The iodine-thiocyanate-sulfur dioxide substance is a new compound

Iodine Monochloride

Iodine monochloride may be prepared in quantity and of superior quality by the reaction between solid iodine and liquid chlorine at -78°: Vapor pressure measurement of iodine monochloride between 30° and 60° indicate that it is a polar substance. If Ammonium chloride or potassium chloride is dissolved in liquid iodine monochloride conducting solutions are formed. When iodine monochloride reacts with common salts and chemical reaction ensues the reaction is usually either direct addition or else is solvolytic

Freezing Point Curves of Iodine Monochloride Mixed with Iodine, Acetic Acid, or Carbon Tetrachloride

The curve obtained with iodine differs from the curve obtained by previous workers; the acetic acid curve approximates expectation based on Raoult\u27s Law; the carbon tetrachloride curve indicates the formation of solid substances

The Influence of pH Values on the Oxidation of Ferrous Sulphate

Weighed quantities of ferrous sulfate were dissolved in buffered solutions after which the resulting buffered solutions of ferrous sulfate were aerated for three hours. The quantity of iron remaining unoxidized after three hours aeration was, in each case determined, by titrating the aerated solution with potassium permanganate solution. The degree of oxidation was found to vary both with the initial concentration of ferrous sulfate and with the pH value of the solution