Bicarbonate, determination

Fig. 11. Calcite saturation index vs depth for Crooks Gap. The water analysis used for the calculations was the original water analysis plus the amount of added calcium and bicarbonate determined from Fig. 7.

The pH determines the overall state of acidosis or alkalosis, and assessments of the Pco and bicarbonate determine if the source is respiratory or metabolic. 

Dissolve the residue obtained in the determination of sodium bicarbonate in the minimum volume of dilute hydrochloric acid and dilute to 100 ml with water. To 10 ml add 200 ml of water and neutralise to methyl orange-xylene cyanol with dilute ammonia solution. Add 20 ml of ammonia buffer solution and titrate with 0 05M EDTA using solo-chrome black. The volume of 0 05 M EDTA plus one tenth the volume of 0 05M EDTA required in the sodium bicarbonate determination represents the amount of Mg present. 1 ml 0 05M = 0 001216 g Mg. 

Some of the critical properties of water change very quickly after sampling. These properties should be determined in the field immediately after the sample is taken in order to determine an acceptable scaling tendency. Two properties that should be determined in this manner to have any value are pH and bicarbonate (HCOj"). The instant that the pressure is reduced, any dissolved acid gases (HjS and COj) will begin to escape from the water and the pH will begin to rise. The loss of dissolved CO2 will have a direct effect on the bicarbonate and carbonate concentrations. Generally only bicarbonate determination is needed carbonate concentration is small. 

Bicarbonate, determination of 213-215 Boiler feed water, determination of anions 88-90... 

Synthetic manganese carbonate is made from a water-soluble Mn (IT) salt, usually the sulfate, by precipitation with an alkafl or ammonium carbonate. The desired degree of product purity determines the quaUty of manganese sulfate and the form of carbonate to be used. For electronic-grade material, where the content of K O and Na20 cannot exceed 0.1% each, the MnSO is specially prepared from manganese metal, and ammonium bicarbonate is used (26) (see Electronic materials). After precipitation, the MnCO is filtered, washed free of excess carbonate, and then, to avoid undesirable oxidation by O2, dried carefljlly at a maximum temperature of 120°C. 

Alkalinity. The alkalinity of a water sample is its acid-neutrali2ing capacity. Bicarbonate and carbonate ions are the predominant contributors to alkalinity in most waters, and their chemical equiUbria generally maintain the pH of 5—9. The presence of enough hydroxide ion to affect the alkalinity determination in natural waters is rare. SiUca, borate, or phosphate do contribute to the overall alkalinity if present in large enough quantities. 

The alkalinity is determined by titration of the sample with a standard acid (sulfuric or hydrochloric) to a definite pH. If the initial sample pH is >8.3, the titration curve has two inflection points reflecting the conversion of carbonate ion to bicarbonate ion and finally to carbonic acid (H2CO2). A sample with an initial pH <8.3 only exhibits one inflection point corresponding to conversion of bicarbonate to carbonic acid. Since most natural-water alkalinity is governed by the carbonate—bicarbonate ion equiUbria, the alkalinity titration is often used to estimate their concentrations. 

Ion chromatography can be used to determine chloride concentrations of 2—1000 ppb with a carbonate—bicarbonate eluent (23). Eluoride, nitrite, phosphate, bromide, nitrate, and sulfate do not interfere and can be measured simultaneously with a total analysis time of <30 min. 

Sepa.ra.tlon, Sodium carbonate (soda ash) is recovered from a brine by first contacting the brine with carbon dioxide to form sodium bicarbonate. Sodium bicarbonate has a lower solubiUty than sodium carbonate, and it can be readily crystallized. The primary function of crystallization in this process is separation a high percentage of sodium bicarbonate is soHdified in a form that makes subsequent separation of the crystals from the mother hquor economical. With the available pressure drop across filters that separate Hquid and soHd, the capacity of the process is determined by the rate at which hquor flows through the filter cake. That rate is set by the crystal size distribution produced in the crystallizer. 

Into a suspension of 8 g of sodium acetate m 400 mL of a solution of 1 part acetic acid and 10 parts fluorotnchloromethane is passed at -75 C a stream of fluonne diluted to 10% with nitrogen The reacuon is stirred with a Vibromixer A solution of 4-methylacetanilide (20 mmol) in a mixture of dichloromethane and fluorotnchloromethane cooled to -75 °C i s added to 20 mmol of acetyl hypofluonte as determined by titration with potassium iodide After 5 min the mixture is poured into water, and the orgamc layer is washed with sodium bicarbonate soluaon and dried over anhydrous magnesium sulfate After concentrauon and column chromatography over silica gel and elution with chloroform, 2-fluoro-4-methylacetanilide IS obtained m 85% yield... 

Before commencing a second determination, the contents of the combustion tube are emptied on to the wire-gauze sieve, placed over one of the tin dishes, and the fine and coarse oxide separated. Both oxides are roasted in order to reoxidise any reduced copper, and transferred as before to their respective flasks. The sodium bicarbonate tube is emptied into a special... 

These are rate constants for the hydrolysis of cinnamic anhydride in bicarbonate-carbonate buffers. The pK of bicarbonate is 10.22. Find the rate constant for hydrolysis, at each pH, at zero buffer concentration. Analyze the data to determine if the acid or base component of the buffer, or both, are responsible for catalysis, and give the catalytic rate constant(s). 

The pH of the mixture was adjusted to 7.5 by adding a saturated sodium bicarbonate solution. After being washed twice with diethyl ether, the reaction solution was acidified to pH 2 with dilute hydrochloric acid and extracted with ether. The ether solution containing the free penicillin was washed twice with water and then extracted with 50 ml of N potassium bicarbonate solution. After freeze drying of the obtained neutral solution, the potassium salt of o-azidobenzylpenicillin was obtained as a slightly colored powder (11.2 grams, 54% yield) with a purity of 55% as determined by the hydroxylamine method (the potassium salt of penicillin G being used as a standard). 

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. 

Alkalinity the total concentration of alkaline salts (bicarbonate, carbonate and hydroxide) determined by titration with acid to pH 4.5. Units are mg/l as CaCOs. 

The most important property of the dissolved solids in fresh waters is whether or not they are such as to lead to the deposition of a protective film on the steel that will impede rusting. This is determined mainly by the amount of carbon dioxide dissolved in the water, so that the equilibrium between calcium carbonate, calcium bicarbonate and carbon dioxide, which has been studied by Tillmans and Heublein and others, is of fundamental significance. Since hard waters are more likely to deposit a protective calcareous scale than soft waters, they tend as a class to be less aggressive than these indeed, soft waters can often be rendered less corrosive by the simple expedient of treating them with lime (Section 2.3). 

Determining calcium levels normally does not identify hardness breakthrough because the calcium salt simply reacts with phosphate precipitant (or similar treatment) and is lost as a sludge. It does, however, produce an immediate and noticeable reduction in alkalinity. (Calcium bicarbonate breaks down to calcium carbonate and carbonic acid.)... 

Danckwerts et al. (D6, R4, R5) recently used the absorption of COz in carbonate-bicarbonate buffer solutions containing arsenate as a catalyst in the study of absorption in packed column. The C02 undergoes a pseudo first-order reaction and the reaction rate constant is well defined. Consequently this reaction could prove to be a useful method for determining mass-transfer rates and evaluating the reliability of analytical approaches proposed for the prediction of mass transfer with simultaneous chemical reaction in gas-liquid dispersions. 

The complexation of Pu(IV) with carbonate ions is investigated by solubility measurements of 238Pu02 in neutral to alkaline solutions containing sodium carbonate and bicarbonate. The total concentration of carbonate ions and pH are varied at the constant ionic strength (I = 1.0), in which the initial pH values are adjusted by altering the ratio of carbonate to bicarbonate ions. The oxidation state of dissolved species in equilibrium solutions are determined by absorption spectrophotometry and differential pulse polarography. The most stable oxidation state of Pu in carbonate solutions is found to be Pu(IV), which is present as hydroxocarbonate or carbonate species. The formation constants of these complexes are calculated on the basis of solubility data which are determined to be a function of two variable parameters the carbonate concentration and pH. The hydrolysis reactions of Pu(IV) in the present experimental system assessed by using the literature data are taken into account for calculation of the carbonate complexation. 

The concentrations of free carbonate and bicarbonate ions determined at solubility equilibrium as a function of pH. Decrements of the concentration near pH = 10 suggest the formation of the Pu(0H)2C03 precipitate and hence lowering solubilities of Pu02 (cf. Figure 2). 

Alkalinity measurement is also required for the determination of active matter by difference and equivalent weight calculations. It can be determined as two of the following compounds sodium bicarbonate, sodium carbonate, or sodium hydroxide. The sample is titrated to a phenolphthalein endpoint to determine the sodium hydroxide/sodium carbonate content. An added measure of acid converts any bicarbonate to carbon dioxide, which is subsequently removed from the solution. Back-titration of the excess acid gives a measure of the amount of bicarbonate and/or carbonate present. 

More straightforwardly, the sample may be titrated potentiometrically using hydrochloric acid to two points of inflexion. The first represents sodium hydroxide plus sodium carbonate the second sodium bicarbonate. Clearly there cannot be bicarbonate in the sample if there is sodium hydroxide present. Any second inflexion in this case can be used to determine the carbonate content. Should the titer from the first inflexion to the second be greater than that from start to the first inflexion, then the sample contains only carbonate and bicarbonate. The titer to the first inflexion can be used to estimate carbonate and the difference between twice this titer and the total titer to the second inflexion is a measure of bicarbonate. 

Rainwater and snowmelt water are primary factors determining the very nature of the terrestrial carbon cycle, with photosynthesis acting as the primary exchange mechanism from the atmosphere. Bicarbonate is the most prevalent ion in natural surface waters (rivers and lakes), which are extremely important in the carbon cycle, accoxmting for 90% of the carbon flux between the land surface and oceans (Holmen, Chapter 11). In addition, bicarbonate is a major component of soil water and a contributor to its natural acid-base balance. The carbonate equilibrium controls the pH of most natural waters, and high concentrations of bicarbonate provide a pH buffer in many systems. Other acid-base reactions (discussed in Chapter 16), particularly in the atmosphere, also influence pH (in both natural and polluted systems) but are generally less important than the carbonate system on a global basis. 

River water chemistry is determined by the relative concentrations of major dissolved components (bicarbonate, calcium ion, silica, and sulfate), which are in turn controlled by the environment. Rivers in precipitation-dominated... 

In addition, the physician with the aid of the clinical chemist, needs to calculate salt and water requirements for the newborn infant. Of prime importance is the determination of how much sodium bicarbonate is required to correct an acidosis, or in rare cases, how much ammonium chloride might be required to correct an alkalosis ( ). 

Hydrolase enzymes catalyze the hydrolysis of a substrate and are most commonly coupled with potentiometericela trodes The pioneering work in this field focussed on de loping an enzyme electrode for the determination of urea. Urease catalyzes the hydrolysis of urea to ammonium and bicarbonate ions according to the reaction detailed below. 

Alkalinity is measured by acid-base titration with methylorange or phe-nolphthalein as indicator. Phenolphthalein changes color at pH 8.3, whereas methylorange changes color at pH 4.3. At pH 8 the neutralization of the strong alkali ingredients like NaOH is essentially complete. Further reduction of the pH to 4 will also measure carbonates and bicarbonates. Colorimetric tests and glass electrode systems are used to determine pH. 

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