Potassium arsenates

A striking example of the importance of narrowing the focus in research, which is what the concept of the parepisteme really implies, is the episode (retailed in Chapter 3, Section 3.1.1) of Eilhard Mitscherlich s research, in 1818, on the crystal forms of potassium phosphate and potassium arsenate, which led him, quite unexpectedly, to the discovery of isomorphism in crystal species and that, in turn, provided heavyweight evidence in favour of the then disputed atomic hypothesis. As so often happens, the general insight comes from the highly specific observation. 

Arsenic trichloride Gallium arsenide Potassium arsenate Arsine Arsenic add Sodium arsenate Sodium arsenite CaicKjm arsenate Arsenic trioxide Arsenic pwtoxide Arsenic bisulphide Arsenic pentasulphide Arsenic hemiselenide... 

The heat sensitivity (above) may explain the explosions which occur on contact of many readily oxidisable materials with this powerful oxidant. Such materials include ammonia, potassium arsenic, antimony sulfur, charcoal (adsorptive... 

M acid ORG chem NH2CioH5(OH)S03H A sulfonic acid formed by alkaline fusion of a disulfonic acid of a-naphthylamine used as a dye intermediate. em, as-3d Macquer s salt See potassium arsenate. mo kerz, s6lt ... 

Potassium arsenate (see Arsenic and arsenic compounds) Potassium arsenite (see Arsenic and arsenic compounds) Potassium bis(2-hydroxyethyl)dithiocarbamate Potassium bromate... 

There is a series of arsenatophosphates corresponding with each of the three forms of condensed potassium arsenate and phosphate, the transition points and melting point of which vary systematically with composition (see Fig. 10). A chain structure for the a-form of potassium arsenate and arsenophosphate may be inferred from their isomorphism with (KP03)xB. The 7-forms also contain high-molecular anionic chains for, when they are hydrolyzed, monoarsenate and polyphosphates with chain length up to n = 6 are formed, depending on their phosphorus content. No metaphosphate is produced, however. 

Potassium Arsenates.—Potassium Orthoarsenate, K3As04, is formed when excess of potassium hydroxide reacts with aqueous arsenic acid 6 or from a mixture of potassium carbonate and potassium monohydrogen arsenate.7 The salt crystallises in needles. The heat of formation is 396,200 calories.8... 

By subjecting potassium arsenate in a slowly moving stream of hydrogen to a silent electric discharge, reduction to arsenic occurs.9 Suitable conditions for this result are to apply 80 volts to the primary circuit and 15,000 volts to the reaction vessel, using a transformer instead of an induction coil the hydrogen should pass at the rate of 2 litres per hour. 

The heat sensitivity (above) may explain the explosions which occur on contact of many readily oxidisable materials with this powerful oxidant. Such materials include ammonia, potassium arsenic, antimony sulfur, charcoal (adsorptive heating may also contribute) calcium phosphide, phosphine, phosphorus hydrogen sulfide, antimony sulfide, barium sulfide, mercury sulfide and tin sulfide [1], Various organic materials (paper, cork, rubber, turpentine, etc.) behave similarly [2]. Mixtures with hydrogen detonate on ignition [1]. 

The formula for potassium arsenate is K3As04. The formula for potassium ferrocyanide, systematically called potassium hexacyanoferrate(II), is K4Fe(CN)g. Write the formulas for (a) calcium arsenate ib) iron(III) arsenate ... 

Potassium arsenates.—Potassium arsenate, K3As04 dipotassium hydrogen arsenate, K2HAs04and potassium dihydrogen arsenate, KH2As04, have been prepared. Their heats of formation are respectively 396-2 Cal., 339-8 Cal., and 234-0 Cal.5 The last mentioned has a density of 2-851 at ordinary temperatures,6 and of 2-8675 at 9-2° C.7 Potassium meta-arsenate, KAs03, has a specific heat of 0-1568 between 17° and 99° C.8... 

POTASSIUM ARSENATE POTASSIUM ARSENATE, MONOBASIC POTASSIUM DIHYDROGEN ARSENATE POTASSIUM HYDROGEN ARSENATE... 

Classify the following elements as metals, metalloids, or non-metals potassium, arsenic, aluminum, xenon, bromine, silicon, phosphorus. 

Chromic Arsenate, CrAsO, is formed as an apple-green precipitate when potassium arsenate is added to a solution of a chromic salt. 

K3As04 potassium arsenate 13464-36-3 25.00 2 8000 1 2409 MgH606S magnesium sulfite trihydrate 19086-20-5 25.00 2.1200 1... 

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