Calcium volumetric

Calcium Place 2.4973 g CaC03 in volumetric flask with 300 ml water, carefully add 10 ml HCl ... 

It is also possible to prepare a standard solution of calcium carbonate accurately using an analytical balance and a volumetric flask, as was suggested previously for EDTA, and pipetting an aliquot (a portion of a larger volume) of this solution into the reaction flask in preparation for the standardization of the EDTA solution. In this case, the concentration of the calcium carbonate solution is first calculated from the weight-volume preparation data (refer back to Example 4.2) and then the molarity of the EDTA solution is determined using Equation (5.54). 

The form of variation of flux (i/r) with voidage (e) and volumetric concentration (C) is shown in Figure 5.18 for a value of n = 4.8. This corresponds to the sedimentation of uniform spheres for which the free-falling velocity is given by Stokes law. It may be compared with Figure 5.4 obtained for a flocculated suspension of calcium... 

Elliot, W. E. Volumetric determination of calcium in blood serum. J. Biol. 

Calcium stock solution, 1000 jg Ca + mh - stock solutions of many elements for determination by AAS are available commercially. Details for in-house preparation will also be given. Anhydrous calcium nitrate, CafNOjfj, is dried for 1 h at 105°C, then cooled in a desiccator. Transfer 2.05 g to a 100-ml beaker containing water and stir to dissolve. Immediately add 1 ml HCI (36% m/m) to prevent hydrolysis, add with washings to a 500 ml volumetric flask, make up to the mark with water, and mix by shaking. 

Sulphate stock standard solution, 500 pg mM of SO -S - dissolve 2.717 g potassium sulphate (K SO ), previously dried at 105°C for 1 h and cooled in a desiccator, in calcium phosphate extractant, then transfer to a 1-1 volumetric flask with washings and make up to the mark with extractant. 

Sulphate working standard solutions, 0-12 pg mM of SO -S - pipette 1, 2, 4, 6, 8 and 12 ml of the 500 pg mh sulphate stock standard solution into 500-ml volumetric flasks, make up to the mark with calcium phosphate extractant and mix. This will give solutions containing 1, 2, 4, 6, 8 and 12 pg mh of sulphate-S. 

The exact amount of acetic acid required by a particular sample of calcium cyanamide is first determined volumetrically as follows A weighed sample of calcium cyanamide (approxi-... 

Filter samples for the stability and repeatability studies were prepared by spiking the filter with a known volume of the dye solution using fixed volume pipettes or volumetric syringes. The filters were then dried in a dessicator filled with anhydrous calcium sulfate and phosphorous pentoxide. The dessicator provided more rapid and uniform drying of the... 

A standard solution was prepared in 50% acetonitrile and water having a known concentration of about 100. ig of glycerin per milliliter. Then 1.0 g of Nasonex was transferred into a 200-mL volumetric flask. About 30 mg of calcium chloride was added and diluted to volume with 50% acetonitrile in water and mixed. A portion of standard and sample solutions were filtered through a 0.45- xm nylon syringe filter. Equal volumes (1. iL) of standard and sample solutions were injected separately into the chromatographic system. 

Chlorine (Note 1) is passed into 300 ml. of anhydrous carbon tetrachloride (Note 2) contained in a 500-ml. three-necked round-bottomed flask equipped with a mechanical stirrer, a dropping funnel protected from atmospheric moisture by a calcium chloride tube, and a gas-inlet tube equipped with a sintered-glass tip (Note 3). The amount of chlorine contained in the resulting yellow-green liquid, estimated volumetrically (Note 4), varies between 25 and 32 g. The gas-inlet tube is replaced by a calcium chloride tube, and the reaction vessel is cooled externally with ice water and protected from light by being covered with a towel. 

It can precipitate as potassium hydrogen tartrate (KHT) or as calcium tartrate (CaT), the latter being practically insoluble in aqueous solutions. Their equilibrium solubility varies with temperature, pH, and alcohol content, while the presence of a few wine components, such as polysaccharides and mannoproteins, may hinder spontaneous nucleation even if the solution is supersaturated. From Figure 14 that shows the equilibrium tartaric acid-dissociated fractions versus pH and ethanol volumetric fraction (Berta, 1993 Usseglio-Tomasset and Bosia, 1978), it can be seen that in the typical pH range (3 4) of wines KHT is predominant. As temperature is reduced from 20 to 0°C, KHT solubility in water or in a 12% (v/v) hydro-alcoholic solution reduces from 5.11 to 2.45 kg/m3 or from 2.75 to 1.1 kg/m3, respectively (Berta, 1993). Each of these data also varies with pH and reaches a minimum at the pH value associated with the maximum concentration of the hydrogen tartrate anions. For the above-mentioned solutions, the solubility minimum shifts from pH 3.57 to pH 3.73 as the ethanol content increases from 0 to 12% (v/v) (Berta, 1993). 

The sulfur sorbent that has received the most attention is limestone because of its widespread availability and low cost. Unfortunately the conversion of limestone to calcium sulfate results in a volumetric increase, and it can be readily shown (8 ) that for particles that do not permit volumetric expansion on reaction the maximum conversion attainable is about 59 percent (the value is dependent on the specific volumes of reactant and product). This constraint can be avoided by use of dolomite, since the MgO is not sulfated and the void volume produced by the decomposition of MgCO and CaCO is sufficient to permit complete calcium utilization, but at the expense of an added weight of sorbent and added energy requirement for calcination. The above conclusions follow from consideration of the stoichiometric relations ... 

Standard Preparation Transfer about 15 mg of USP Calcium Pantothenate Reference Standard, previously dried at 105° for 3 h and accurately weighed, into a 25-mL volumetric flask. Dilute to volume with Internal Standard Preparation, and mix. 

Stock Calcium Solution Transfer 124.8 mg of calcium carbonate (CaC03) previously dried at 200° for 4 h, into a 100-mL volumetric flask, carefully dissolve in 2 mL of 2.7 A hydrochloric acid, dilute to volume with water, and mix. This 500-mg/kg calcium solution is commercially available. 

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