Oxalic acid, determination

Measuring and Using Numbers From the mass of oxalic acid used and the molar mass of oxalic acid, determine and record the number of moles of oxalic acid. 

Urinary Oxalic Acid Determined by Gas Chromatography (Primary Report)... 

A balanced chemical reaction indicates the quantitative relationships between the moles of reactants and products. These stoichiometric relationships provide the basis for many analytical calculations. Consider, for example, the problem of determining the amount of oxalic acid, H2C2O4, in rhubarb. One method for this analysis uses the following reaction in which we oxidize oxalic acid to CO2. 

The balanced chemical reaction provides the stoichiometric relationship between the moles of Fe used and the moles of oxalic acid in the sample being analyzed— specifically, one mole of oxalic acid reacts with two moles of Fe. As shown in Example 2.6, the balanced chemical reaction can be used to determine the amount of oxalic acid in a sample, provided that information about the number of moles of Fe is known. 

The amount of oxalic acid in a sample of rhubarb was determined by reacting with Fe as outlined in reaction 2.2. In a typical analysis, the oxalic acid in 10.62 g of rhubarb was extracted with a suitable solvent. The complete oxidation of the oxalic acid to CO2 required 36.44 mb of 0.0130 M Fe. What is the weight percent of oxalic acid in the sample of rhubarb ... 

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. 

The calcium carbonate precipitate was removed by filtration, and the filtered solution was found to contain 1,436 g of fructose as determined by optical rotation. A small amount of calcium bicarbonate was present as an impurity in solution and was removed by the addition of oxalic acid solution until a test for both calcium and oxalic acid was negative. The insoluble calcium oxalate precipitate was removed by filtration. 

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. 

Mandal and Hay28 used MALDI-TOF mass spectrometry to determine the absolute molecular masses and endgroups of 4-phenylphenol novolac resins prepared in xylene or chlorobenzene. Peaks with a mass difference of 44 (the molecular weight of a xylene endgroup) suggested that reactions conducted in xylene included some incorporation of xylene onto the chain ends when a strong acid such as sulfuric acid was used to catalyze the reaction. By contrast, no xylene was reacted into the chain when a milder acid catalyst such as oxalic acid was used. No chlorobenzene was incorporated regardless of the catalyst used. 

L.10 A sample of oxalic acid, H,C,04 (with two acidic protons), of volume 25.17 mL was titrated to the stoichiometric point with 25.67 mL of 0.327 M NaOH(aq). (a) What is the molarity of the oxalic acid (b) Determine the mass of oxalic acid in the solution. 

Preceding papers. h Preliminary values obtained through redetermination of parameters in crystals (cal-cite and sodium nitrate) by Mr. Norman Elliot. The values in parentheses are based on older parameter determinations. c L. Pauling and L. O. Brockway, Proc. Nat. Acad. Sci., 20, 336 (1934). The value 1.25 A. reported in crystals of oxalic acids and oxalates is probably less reliable. 

Saccharic acid. Use the filtrate A) from the above oxidation of lactose or, alternatively, employ the product obtained by evaporating 10 g. of glucose with 100 ml. of nitric acid, sp. gr. 1 15, until a syrupy residue remains and then dissolving in 30 ml. of water. Exactly neutrally at the boiling point with a concentrated solution of potassium carbonate, acidify with acetic acid, and concentrate again to a thick syrup. Upon the addition of 50 per cent, acetic acid, acid potassium saccharate separates out. Filter at the pump and recrystallise from a small quantity of hot water to remove the attendant oxalic acid. It is necessary to isolate the saccharic acid as the acid potassium salt since the acid is very soluble in water. The purity may be confirmed by conversion into the silver salt (Section 111,103) and determination of the silver content by ignition. 

Bogdanov, S., Charriere, J. D., Imdorf, A., Kilchenmann, V., and Fluri, P. (2002). Determination of residues in honey after treatments with formic and oxalic acid under field conditions. Apidologie 33, 399-409. 

Del Nozal, M. J., Bernal, J. L., Gomez, L. A., Higes, M., and Meana, A. (2003b). Determination of oxalic acid and other organic acids in honey and in some anatomic structures of bees. Apidologie 34,181-188. 

In this activity, you will first standardize a NaOH solution by using the solution to titrate a known mass of oxalic acid (H2C204). Then, you will use your standardized solution to titrate a sample of vinegar. Vinegar is a solution of acetic acid (HC2H302). From your titration data, you will be able to calculate the number of moles and the mass of the acetic acid in your vinegar sample and determine the percent of acetic acid in vinegar. 

Applying Concepts Use the moles of oxalic acid calculated in question 1 and the mole ratio from question 2 to determine the moles of NaOH. 

Mayer, W. J. and Greenberg, M. S., A comparison of differential pulse and D. C. amperometric detection modes for the liquid chromatographic determination of oxalic acid, /. Chromatogr Sci., 17, 614, 1979. 

The amount of oxalic acid thus decomposed under conditions where all the light is absorbed by the uranyl ion is determined by titrating a sample of the solution with potassium permanganate before and after irradiation. Since... 

The structure of the levan synthesized by the action of B. subtilis on sucrose was determined by Hibbert and Brauns.89 Levan, in a yield of 60-65% calculated on the D-fructose part of the sucrose, was obtained by precipitation of the concentrated culture into methanol, and purified by reprecipitation and electrodialysis. Hydrolysis of purified levan with 0.5% aqueous oxalic acid for one hour at 100° gave a 99% yield of crystalline D-fructose. Triacetyllevan was prepared by treatment with acetic anhydride in pyridine, and deacetylation with alcoholic alkali yielded material identical with the original levan.940... 

Procedures for pretreatment of soil samples and synthesis of sample benzene for 14C analysis had been described in Chen et al. (2002b). Sample benzene was often left for 3-4 weeks to allow any radon with half-life of 3.82 days that may be present to decay. 14C activity of the CgFL was then determined using a 1220-QUANTULUS ultralow-level liquid scintillation spectrometer manufactured by WALLAC Company, Sweden. The 14C analyses were conducted at the Guangzhou Institute of Geochemistry, CAS. Results are reported as A14C, in parts per thousand of the 14C/12C ratio from that of the standard (oxalic acid decay corrected to 1950) (Stuiver and Po-lach 1977), and corrected for bomb 14C (Chen et al. 2002b), where ... 

A mixture consisting of oxalic acid, carbodiimide, fluorescer, and hydrogen peroxide is known to produce strong visible light [185], Albrecht et al. used this reaction to determine oxalate in urine [118] and serum [119]. 

The mass of oxalic acid enables us to determine the amount of NaOH in the solution. 

In a study by Fincke and Sherman (JL3), the calcium of spinach was not utilized as well as that from milk however, the calcium of kale, which is low in oxalic acid (3,4), was about as available as that from milk. The calcium utilization factor was determined by dividing the weight of calcium stored by the weight of calcium ingestion. Rats 4 weeks old were fed for 60 days a diet in which most of the calcium was supplied by skim milk, or in which half of the skim milk was replaced by dried spinach or dried kale in amounts to provide the same amount of calcium. The diets contained about 0.3% calcium and 10% butter fat. It was concluded that the poor utilization of the calcium of spinach was due to the oxalic acid in spinach. 

Spiers (18) reported that the feeding of 14% dried New England spinach in the diet resulted in decreased growth and less calcium retention, as determined by body calcium content (Figure 3). Rats 28 days old were fed until 60 days of age. All diets contained about 0.3% calcium, and in the control diet practically all of the calcium was from skim milk. In the other diets, one-half of the skim milk was replaced by turnip greens, tendergreens, collards, kale, or New Zealand spinach to furnish an equal amount of calcium. Spinach was the only one of the greens fed which contained considerable oxalic acid. The calcium of the spinach appeared not only to be utilized poorly, but spinach also impaired utilization of the milk calcium. Food intake of the rats on the spinach diet was also lower. 

Lovelace et al. (20) noted that the effect of oxalic acid on calcium retention depended on the age of the animal (Figure 4). The two experimental diets contained cod liver oil and 0.3% calcium. Milk was the main source of calcium, and to one diet was added 60 mg of potassium oxalate daily. Ten-day balances were determined throughout the study until rats were 175 days of age. At 50 days of age, rats fed oxalate retained about 25% of the calcium,... 

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