Oxalic acid equivalent

Oxalate Acid Number. A metal soap solution is treated with a measured excess of organic acid. Potassium oxalate solution is added to precipitate the metal and the total sample is back-titrated with alkaU to determine its acidity. Acidity is expressed ia acid number units, equivalent to mg KOH per g. A neutral soap gives a 2ero acid number, an acidic soap solution a positive acid number, and a basic soap solution a negative acid number. 

Morpholine [110-91-8] M 87.1, f -4.9", b 128.9", d 1.0007, n 1.4540, n 5 1.4533, pK 8.33. Dried with KOH, fractionally distd, then refluxed with Na, and again fractionally distd. Dermer and Dermer [J Am Ghent Soc 59 1148 1937] ppted as the oxalate by adding slowly to slightly more than 1 molar equivalent of oxalic acid in EtOH. The ppte was filtered and recrystd twice from 60% EtOH. Addition of the oxalate to cone aq NaOH regenerated the base, which was separated and dried with solid KOH, then sodium, before being fractionally distd. 

Hydrocarbon A has the formula C Hg- It absorbs 8 equivalents of H2 on catalytic reduction over a palladium catalyst. On ozonolysis, only two products are formed oxalic acid (H02CC02H) and succinic acid (H02CCH2CH2C02H). Write the reactions, and propose a structure for A. 

Neutralisation reactions. The equivalent of an acid is that mass of it which contains 1.008 (more accurately 1.0078) g of replaceable hydrogen. The equivalent of a monoprotic acid, such as hydrochloric, hydrobromic, hydriodic, nitric, perchloric, or acetic acid, is identical with the mole. A normal solution of a monoprotic acid will therefore contain 1 mole per L of solution. The equivalent of a diprotic acid (e.g. sulphuric or oxalic acid), or of a triprotic acid (e.g. phosphoric( V) acid) is likewise one-half or one-third respectively, of the mole. 

Here the change in oxidation number per atom of iron is from +2 to +3, or by 1 unit of oxidation, hence the equivalent of iron(II) sulphate is 1 mole. Another important reaction is the oxidation of oxalic acid to carbon dioxide and water ... 

Wittwer and Zollinger (1954) determined the neutralization curves of aqueous solutions of diazonium salts under standard conditions of ionic strength, etc., and found that the acidity depended on the degree of neutralization in a manner different to that expected for a dibasic acid. The curve obtained did not exhibit two steps with an intermediate region of a few pH units in which the monobasic acid is stable, as is the case, for instance, with oxalic acid (Fig. 5-1). On the contrary, there was only one step, but it extended over two equivalents of base per diazonium ion. 

When the three ligands are the same, procedures similar to the ones developed by Hellwinkel [16,17], Koenig [25-28] and coworkers can be utilized -that is the one-time addition of three equivalents of bidentate ligands to PCI5 to afford the hexacoordinated phosphate anions. Ligands as varied as malonic acid,3,3,3-trifluoro-2-hydroxy-2-trifluoromethyl-propionic acid or oxalic acid have been used to form 5,6, and 7,respectively [29]. Aromatic 1,2-diols are also particularly good ligands as tetrachloropyrocatechol [30, 31], 4-methylpyro-... 

In the reaction given, two hydrogens are lost per molecule of oxalic acid. The equivalent weight is therefore the formula weight divided by 2, or 63.035 g per equivalent. The equivalents of oxalic acid used here are calculated by dividing the weight (of the hydrate) by the equivalent weight. Then normality is calculated... 

Procedure Weigh accurately about 1 g of sodium nitrite and dissolve it in DW to make 100 ml in a volumetric flask. Transfer 10 ml of this solution into a mixture of 50 ml of 0.1 N KMn04, 100 ml of water and add 5 ml of sulphuric acid along the side of the flask. Heat the contents to 40°C, allow it to stand for 5 minutes and add 25 ml of 0.1 N oxalic acid. Warm the resulting mixture to about 80°C on a steam-bath and titrate with 0.1 N KMn04 solution. Each ml of 0.1 N potassium permanganate is equivalent to 3.450 mg of NaN02. 

It should be noted that addition of the tributyltin radical to 1-fluoro-1-(phenylsulfonyl)ethene provides phenyl vinyl sulfone as the only isolated product. However, 2-trimethylsilyl-1-fluoro-1-(phenylsulfonyl)ethene reacts with tributyltin hydride in the presence of AIBN to provide (E)-2-trimethylsilyl-1-fluoro-1-tributylvinylstannane. The vinylstannane is an equivalent for the synthon "H2C=CF " providing a convenient route to 2-fluoro-1-alkenes.8 The trimethylsilyl group can be removed with potassium fluoride in dimethyl sulfoxide-water or oxalic acid-methanol at the end of the reaction sequence. 

The erbium ion is coordinated to eight carboxyhc oxygens [2.362—2.415 A)] from four oxalate (acid oxalate) moieties which forms a square antiprism around Er(III). A water molecule forms the cap (Er—OH2 =2.441 A) above the large square face of the antiprism. The acid oxalates (HOOCCOO) and oxalate ions occupy the crystallographic sites at random. The statistically averaged oxalate groups are centrosymmetric and planar. A very short H-bond (2.43 A) has been observed between two water molecules in two equivalent molecules, but the physical significance is difficult to assess because these waters are disordered in the molecule. 

Then, 205 mg of oxalic acid dihydrate is introduced. A further aliquot (13 mol) of KF reagent must next be added to attain a new equivalence point. Finally 10 ml of the same solvent containing 1.05 g of dissolved powdered milk is introduced. Again KF reagent (12 ml) is added to find a final equivalence point. 

Dr. Normandy has proposed a bine ink, which is made by operating upon Chinese blue, or ferrocyanide of iron. Three drachms of the ferrocyanide are macerated in seven ounces of wafer, with one drachm of binoxa-late of potassa, adding one drachm of gum-arabic. A solution of tin may be added to these ingredients the binoxalato of potassa may also be substituted by an equivalent proportion of oxalic acid. 

The equivalence point occurs when the quantity of added titrant is the exact amount necessary for stoichiometric reaction with the analyte. For example, 5 mol of oxalic acid react with 2 mol of permanganate in hot acidic solution ... 

If the unknown contains 5.000 mmol of oxalic acid, the equivalence point is reached when 2.000 mmol of Mn04 have been added. 

The equivalence point is the ideal (theoretical) result we seek in a titration. What we actually measure is the end point, which is marked by a sudden change in a physical property of the solution. In Reaction 7-1, a convenient end point is the abrupt appearance of the purple color of permanganate in the flask. Prior to the equivalence point, all permanganate is consumed by oxalic acid, and the titration solution remains colorless. After the equivalence point, unreacted Mn04 accumulates until there is enough to see. The first trace of purple color is the end point. The better your eyes, the closer will be your measured end point to the true equivalence point. Here, the end point cannot exactly equal the equivalence point, because extra Mn04, beyond that needed to react with oxalic acid, is required to exhibit purple color. 

The difference between the end point and the equivalence point is an inescapable titration error. By choosing a physical property whose change is easily observed (such as pH or the color of an indicator), we find that the end point can be very close to the equivalence point. We estimate the titration error with a blank titration, in which we carry out the same procedure without analyte. For example, we can titrate a solution containing no oxalic acid to see how much Mn04 is needed to produce observable purple color. We then subtract this volume of Mn04 from the volume observed in the analytical titration. 

It is apparent that there are two equivalents per mole of oxalic acid. Hence, a 0.100 N solution will be 0.050 0 M ... 

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