Dissociation Of Formic Acid Research Articles

Oxydation de l'acide formique sur électrode d'or

Summary The anodic oxidation of formic acid on gold electrodes has been investigated in aqueous sulphate electrolyte as a function of pH (0.2 to 8.0), and temperature (30°C to 80°C). The faradaic yield was found to be 100% according to the overall reaction HCOOH=2H aq + +2 e − +CO 2 . Voltage sweep measurements give current vs. potential curves independent of sweep rates (from 10 mV s −1 to 10 V s −1 ). Mechanistic criteria have been deduced from the transfer coefficient, the heat of activation, and the reaction orders with respect to formic acid and H + ion. Around the pH corresponding to the p K (≈3.8), the transfer coefficient varies varies sharply from 0.20 to 0.50, and the reaction order with respect to H + from −0.65 to 0.15. These results have been attributed to a change in the reaction mechanism due to a change in the electroactive species: undissociated formic acid HCOOH for pH K and formate ion HCOO − for pH>p K . In acid medium a mechanism involving the dissociation of formic acid into an adsorbed formate anion and a solvated proton is proposed. This equilibrium is followed by a rate determining one electron transfer step. In neutral medium the overall reaction is controlled by the adsorption of the HCOO aq − anion.

Laser action in a flowing mixture of formic acid, nitrogen, and helium

Laser action has been observed in an electrically excited mixture of formic acid, nitrogen, and helium. The source of population inversion is shown to be CO 2 molecules that are formed by the dissociation of formic acid.

Mechanisms and kinetics of aqueous formic acid and formate ion dehydrogenation on platinum and subsequent reaction of adsorbed hydrogen

The opencircuit chemical behavior of dissolved HCOOH and HCOONa at Pt electrodes was studied. A doublepulse electrochemical anodic charging technique was used to first strip the surface and to then quantitatively determine the amount of atomic hydrogen formed on the clean electrode from the dissociation of formic acid and formates and the net rate at which this atomic hydrogen was removed from the electrode surface by reaction with formate species. The integrated rates of the reaction of PtO ads with hydrogen and/or formate species, of the dehydrogenation of formic acid and formates on clean Pt, and of the atomic hydrogen removal were measured. The kinetics of the net atomic hydrogen removal process were determined and shown to be first order in respect to hydrogen atom concentration at the surface. The formation of residues from the organic free radicals which were the products of dehydrogenation retarded the further dissociation of formic acid and formates. Sulfuric acid solutions of very low pH values and molecular hydrogen could strongly affect the reaction rates and retarded the rate of hydrogen atom removal from the electrode surface. Generalizations concerning fuel cell anodic reactions are made.

Ionization and Dissociation of Formic Acid, Acetic Acid, Propanoic Acid, and Butanoic Acid under Electron Impact

Abstract The mass spectra of DCOOD, DCOOH, CD3COOD, CD3COOH, CH3COOD, C2H5COOD, and C3H7COOD are compared with spectra of the H-containing compounds. Besides, the 18O-labeled acetic acid is measured. The labeling helps to determine the origin of a number of fragment ions. It is found that the two fragment ions C3H5O2+ and C4H7O2+ are produced by the removal of the hydrogen atom from the alkyl group and have the structures of C2H4CO2H+ and C3H6CO2H+ respectively. Neither CH2CO2H+ nor CH3CO2+ is produced. The rerrangement ion CH3O+ is found to have the structure of CH2OH+, one of whose hydrogen atoms comes from the carboxyl group. The origins of the hydrogen atom and the oxygen atom in the other rearrangement ions are also determined. The mechanisms for the fragmentation of the molecular ions are discussed.

Interaction of Carbon Dioxide with Hydrogen Chemisorbed on a Platinum Electrode

The effect of on the oxidation of hydrogen atoms chemisorbed on a Pt electrode has been examined with potentiostatic and transient galvanostatic techniques. The results indicate that is not reduced, but that oxidation is inhibited by , or possibly . Under these conditions the inhibited or blocked Had is stable at potentials negative to 0.3v (vs. NHE). Dissociation of formic acid to and may inhibit the further oxidation of by a similar blocking mechanism.

Dissociation of Formic Acid and Deuteroformic Acids by Ion-Molecule Collision

The dissociation of 5.1 kev HCOOH+, DCOOH+, and HCOOD+ ions by ion-molecule collision with H2, D2, He, N2, A, and Kr has been investigated in a mass spectrometer. Approximate values for the cross sections for the resultant fragment ions have been calculated. Positive ion fragments CHO+ and CHO2+. are produced by loss of hydrogen from both of the possible positions. However, rupture of the C–H bond is a factor of two more probable than cleavage of the O–H bond in the formation of CHO2+. The CHO+ ion fragment is formed mainly by removal of the hydroxyl group.