Oxalate ions

Oxidation states can be used to establish the stoichiometry for an equation. Consider the reaction between the manganate(VII) (permanganate) and ethanedioate (oxalate) ions in acidic solution. Under these conditions the MnO faq) ion acts as an oxidising agent and it is reduced to Mn (aq), i.e. 

In addition to the oxide carboxylates, beryllium forms numerous chelating and bridged complexes with ligands such as the oxalate ion C204 , alkoxides, /9-diketonates and 1,3-diketonates. These almost invariably feature 4-coordinate Be... 

Osmotic pressure The pressure that must be applied to a solution to prevent osmosis, 271-273 cucumbers, 273 maple syrup, 277-278 prunes, 273 Ostwald, Wilhelm, 86 Overall order, 290 Oxalate ion, 411 Oxalic acid, 277... 

In the laboratory you have observed the reaction of ferrous ion, Fe+i(aq), with permanganate ion, MnOiYaqJ, and also the reaction of oxalate ion, CiOi2(aq), with permanganate ion, MnO (aq). These studies show that the rate of a reaction depends upon the nature of the reacting substances. In Experiment 14, the reaction between IO and HSO3" shows that the rate of a reaction depends upon concentrations of reactants and on the temperature. Let us examine these factors one at a time. 

Both ferrous ion, Fe+2(aq) and oxalate ion, Cf)t2(aq), have the capability of decolorizing a solution containing permanganate ion at room temperature. Yet, there is a great contrast in the time required for the decoloration. The difference lies in specific characteristics of Ft+2(aq) and Cf 2(aq). On the other hand, Fe+2(aq) is also changed to Fe+ (aq) by reacting either with MnO fagJ or with ceric ion, Ce+i(aq). One of these reactions is simple and the other involves... 

An example of catalytic action is provided by the titration of oxalates with potassium permanganate solution referred to above. It is found that even though the oxalate solution is heated, the first few drops of permanganate solution are only slowly decolorised, but as more permanganate solution is added the decoloration becomes instantaneous. This is because the reaction between oxalate ions and permanganate ions is catalysed by the Mn2+ ions formed by the reduction of permanganate ions ... 

Oxalates. Urea may be employed to raise the pH of an acid solution containing hydrogenoxalate ion HC2O4, thus affording a method for the slow generation of oxalate ion. Calcium oxalate may thus be precipitated in a dense form ... 

Dimethyl oxalate and diethyl oxalate can also be hydrolysed to yield oxalate ion ... 

Calcium can be determined as the oxalate by precipitation from homogeneous solution by cation release from the EDTA complex in the presence of oxalate ion.28... 

The condition K2>KX has far-reaching consequences. Consider the diazonium ion during neutralization one hydroxide ion is taken up but, unlike the oxalate ion, it cannot rest after the first stage. The diazohydroxide formed must lose a proton immediately to yield the diazoate, a second hydroxide ion acting as proton acceptor. In other words, the diazohydroxide is not a stable intermediate and is not present in aqueous solution in appreciable concentration. It follows that the diazohydroxide... 

The activation energy found for the decomposition of an individual oxalate ion in a KBr matrix (270 15 kJ mole-1) [292,294] is regarded as the energy requirement for C—C bond rupture. The generally lower values of E observed for many oxalates ( 165—175 kJ mole-1) are attributed to the facilitation of reaction at the reactant—product interface. 

Guslev et al. [1155] confirm the increase in stability of (Ni,Mg) oxalates with increase in magnesium content. These workers suggest that the impurity cation in the solid solution (i.e. that which is present at the lower concentration) disturbs the symmetry of the oxalate ion, so promoting its breakdown. 

Write the I ewis structure, including resonance structures where appropriate, for (a) the oxalate ion, C2042 (there is a... 

Write the two proton transfer equilibria that show the amphiprotic character of (a) H2P04 (b) HC204, hydrogen oxalate ion. Identify the conjugate acid-base pairs in each equilibrium. 

Prefers to the electrode coverage with n-butanol. ox = oxalate ion. 

C18-0121. Zinc forms an octahedral complex ion with three bidentate oxalate ions ... 

In acidic solution MnOj is usually the end product, although particularly vigorous reductants, e.g. iodide and oxalate ions, convert permanganate to manganous ions. Mn(III) is stable only in acidic solution or in the form of a complex, e.g. with pyrophosphate ion, and it has seldom been reported as the end product of a permanganate oxidation, e.g. for that of Mn(II) in a phosphate buffer and for those of alcohols and ethers in the presence of fluoride ion. ... 

Cu(II) also catalyses the persulphate oxidation of numerous substrates, for example that of oxalate-ion with a rate law ... 

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