Hydrogen chromate

The reaction between arsenic(III) and chromium(VI) in 0.01-0.05 M sulphuric acid was studied by DeLury . On recomputing his data" taking into consideration the dichromate-hydrogen chromate equilibrium... [Pg.521]

Oxidation of isopropyl alcohol (H2R) by chromic acid has been studied in det ai by Westheimer and Novick , and it was found that acetone (R) is formed nearly quantitatively. The reaction proved to be first order with respect to hydrogen chromate and second order with respect to hydrogen ions. Measurements using 2-deutero-2-propanol under identical conditions as those for the oxidation of ordinary isopropyl alcohol showed the rate of reaction to be of that with the hydrogen compound. This fact is considered to prove that the secondary hydrogen atom is removed in the rate-controlling step and that the assumption of hydride-ion abstraction can be excluded. The data are consistent with the following mechanism... [Pg.525]

A recent study by Lee and Stewart confirms the previous observations that with rather low acid concentrations the oxidation rate of H2R depends only on the acidity of the medium and not on the nature of the proton-supplying mineral acid. On the contrary, at rather high acid concentrations the rate of oxidation depends not only on the acidity but also on the nature of the acids. This can be explained by the fact that the hydrogen chromate and the acid present interact with each other... [Pg.525]

Benzenol can be oxidized to 1,4-benzenedione (pnra-benzoquinone) by chromic acid. The reaction may proceed by way of phenyl hydrogen-chromate... [Pg.1300]

Fortunately the same audiors report a far more pleasant and less hazardous procedure utiliztng a polymer-siqtpoited hydrogen chromate ion (equation 40). The yieids are all in excess of 9S%, and the experiment simpUcity is commendable. [Pg.664]

There is also present in the solution some hydrogen chromate ion, HCrOr ... [Pg.520]

Reaction of chromic anhydride (CrOg) with t-butanol yields t-butyl hydrogen chromate, a powerful oxidant suitable for allylic oxidation of electron-deficient alkenes. Oxidations using t-BuOCr03H in CCI4 are highly exothermic and should be performed with caution. [Pg.100]

The ET step from AcrH2 to hydrogen chromate ions (P CrCU) is also reported to initiate the oxidation of AcrH2 to AcrH + in H20/MeCN (4 1, v/v) via a radical chain mechanism that is strongly inhibited by oxygen.70... [Pg.69]

Metal Cleaner Chromic acid is used as an industrial cleaner for metals. What is for the second ionization of chromic acid (H2Cr04) if a 0.040M solution of sodium hydrogen chromate has a pH of 3.946 ... [Pg.673]

A Raman spectrophotometer was used to measure in situ the polymerisation rate of acrylamide photoinitiated by hydrogen chromate anion in aqueous solution upon irradiation by laser beam (ionised argon)... [Pg.22]

A Raman spectrophotometer was used to measure in situ the polymerisation rate of acrylamide photoinitiated by hydrogen chromate anion in aqueous solution upon irradiation by laser beam (ionised argon). The progress of the reaction was monitored at 2930/cm, the absorption characteristic of the polymer formed. The method was found to be reliable, but is limited to monomers whose polymer is soluble in the reaction medium. 10 refs. EUROPEAN COMMUNITY FRANCE WESTERN EUROPE... [Pg.125]

The hydrolysis kinetics at low alkalinity were also measured, by using an anucleophilic buffer of lutidine/lutidinium ion at pH 8. The rate constant for this reaction (Cr O + H O 2 HCrO ) agreed well with that obtained recently by a relaxation method (8). Arrhenius parameters for this and for the ammonia-catalysed hydrolysed (7) are being obtained, and it is hoped to report on the acid-catalysed interconversion (9) of hydrogen chromate and bichromate ions. [Pg.288]

The transpassive dissolution of chromium produces different hexavalent species chromic acid (H2Cr04), chromate ions (CrOl"), hydrogen chromate ions (HCrO ) and bichromate ions (Cr207 ). The relative concentrations of these species are determined by the following equilibria ... [Pg.601]

Chromium exists primarily as Cr(III) and Cr(VI). Speciation is very important because Cr(VI) is far more toxic than the trivalent species. The actual form of hex-avalent chromium is pH-dependent. Between pH 2 and 6 the yellow chromate, HCr04, and the more intensely colored orange-red dichromate, Cr207 , are in equilibrium. In very dilute aqueous solutions most of the chromium is present as the hydrogen chromate ion, but dichromate is the predominant species around 0.1 M. In basic solution, HCr04 is the major species. Under strongly acidic conditions, only dichromate ion exists. Cr(III) species in acidic solution exist as Cr(H20)5 ions and in concentrated alkali have been identified as Cr(OH)5 and Cr(0H)5(H20)2-. [Pg.359]

Calculate foe pH at foe equivalence point in titrating 0.100 M solutions of each of foe following wifo 0.080 M NaOH (a) hydrobromic add (HBr) (b) lactic acid (HC3H5O3) (c) sodium hydrogen chromate (NaHCi04). [Pg.698]

Picolinic acid has been found to act as a catalyst in the oxidation of isopropyl alcohol by chromic acid. The rate, at constant acidity, is first-order in picolinic acid, hydrogen chromate, and isopropyl alcohol concentrations and the acidity dependence... [Pg.45]

There is formation of hydrogen chromate ions (or acidic chromate ions) and also of dichromate ions (see Chap. 20). Due to the former equilibrium, if the pH value is too low, the concenttation [Cr04 ] is considerably lowered and the solubility product ATs(Ag2Cr04) = [Ag+] [Cr04 ] is never reached. The change at the final point is... [Pg.695]

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