Calcium solubility products, calculation

This Is about half the value of the solubility product calculated using the NBS data that assumes complete dissociation. Since the amount of calcium and sulfate ions in solution are so low and the association of the two to form an aqueous molecule would have little effect on the ionic strength, it may be decided to disregard the interaction. The large difference in the solubility products points out that care must be taken in matching the thermodynamic data to the modeling method chosen. 

Calculate the solubility, in moles per liter, of calcium sulfate in water, using the solubility product given in Table 10-11. 

If S moles of CaCC>3 dissolve in a liter of water, then S moles each of calcium ion and carbonate ion form. With these ion concentrations equal to S, the solubility of CaCC>3 is calculated as 9.3 x 10 5 M. The higher solubility of magnesium carbonate in water, 6.3 x 10 3 M, results from the larger solubility product constant. Nevertheless, both of these carbonate salts are rather insoluble, and the excess carbonate anions provided by the sodium carbonate effectively precipitate the calcium and magnesium ions from solution. 

Equilibrium with precipitation. The previous example calculated carbonate speciation admitting unrestricted solubility of all species. Actually, it is easily verified that the calculated calcium and carbonate concentrations exceed calcium carbonate solubility as measured by the solubility product... 

Application 1.—The solubility of calcium carbonate at 180 is 14 mg. per liter. The solubility product of the salt is therefore very small (calculate this). 

Three approaches have been used in attempting to account for the buffer behavior of milk in terms of the properties of its components. These are calculation, fractionation, and titration of artificial mixtures. Whittier (1933A.B) derived equations for dB/dpH in calcium phosphate and calcium citrate solutions, taking into account available data on dissociation constants and solubility products. Presumably this approach could be extended to calculate the entire buffer curve. It demands precise knowledge of the dissociation constants of the several buffers, the dissociation of the calcium and magnesium complexes, and the solubility products of the calcium and magnesium phosphates under the conditions of a titration of milk. 

Calculation of Apparent Calcium Carbonate Solubility Products The precise determination of the solubility of calcite... 

Published reports discussing the influence of calcium carbonate solid surfaces on the phosphate ion concentration in natural water (2, 3) include 1)solubility product-based calculations 5) iTspontaneous precipitation experimehts from highly supersaturated solutions 7j 9) 3) adsorption of phosphate onto calcium carbonate (10, 11, 12, 13), These experiments have provided useful information, but several have not included activity coefficient or ion pair corrections in their analyses, seriously limiting the applicability of the results. 

Sediment phosphorus extraction analyses show that hydrous iron oxides (extracted by (NH4)2C204) play a major role in the transport of sediment phosphorus. In northern areas of the Genesee River watershed calcium carbonate formation also appears to be Involved in phosphorus fixation. Ion activity product calculations for water column samples from the Genesee River consistently exhibit subsaturation with respect to the stable calcium phosphate phase, hydroxyapatite. Calcium carbonate, which can serve as a substrate for phosphate mineralization, shows an ion activity product below the solubility product in the Genesee River except during the summer low-rainfall season. 

The mineral gypsum has the formula CaS04 2H20, its solubility product being 2.4 X I0 Calculate the solubility of calcium sulfate in... 

EXAMPLE 7-2 The solubility product of calcium fluoride is 4 x 10 Calculate its solubility S, neglecting hydrolysis of fluoride and assuming 5 equal to zero. 

How well can we presently determine the saturation-horizon depth (where D = 1) for calcite in the sea If we assume that we know the calcium concentration exactly, then the error in D is determined by the errors in and the measured carbonate ion concentration, [CO ]. Mucci (1983) was able to determine repeated laboratory measurements of the apparent solubility product, p, at 1 atm pressure to — 5%, and the pressure dependence at 4 km is known to 10%. These errors compound to 11% in the value of K sp (4 km). Carbonate ion concentrations in the sea are almost always calculated from Ax and Die. Being slightly conservative about accuracy of these values in ocean surveys ( 4p.eqkg for Ax and 2p.molkg for DIG they can be determined with errors about half these values if conditions are perfect), and assuming we know exactly the value of the... 

Calculate the solubility product constant for calcium carbonate, given that it has a solubility of 5.3 X 10 g/L of water. 

The rather large solubility product of calcium selenite suggests that the reaction in the calorimeter was not complete. It is estimated that a few per cent of the components remained unreacted. No correction has been applied for this fact. The calculation of the standard enthalpy of formation of CaSe03 H20 with new auxiliary data is shown in Table A-31. 

The primary solubility data and the calculation of the solubility products, defined in the usual way, are presented. This presentation contains some unexpected results. The total solubility of the metal ion and selenite are approximately equal in water and in the inert salt solutions for the magnesium and manganese selenites. This is the expected result for a simple dissolution reaction. For calcium selenite, the metal ion concentration was about 100 times greater than the total selenite concentration whereas for zinc selenite the opposite was found. There is no comment in the paper on these results, which contradict the equilibrium reactions used in the paper to define the reported solubility products for calcium and zinc selenite. The review also noted that the calculation of the magnesium and selenite activities from the total concentrations introduces activity coefficients between 0.1 to 0.01 at moderate ionic strengths. Thus the values of these coefficients appear unreasonably small. On the whole, the activity coefficient corrections introduced appear to vary in an erratic way between the various systems studied. 

Observation Saturated calcium sulfate solution shows a good electrical conductivity. The saturated solution and the 0.01 molar solution of magnesium sulfate produce similar reading on the conductivity tester. This concentration can therefore be used for the calculation of the solubility product of calcium sulfate. 

For the calculation of pHg it is possible to derive the following equation from the equation for the second dissociation constant of carbonic acid K2 and the solubility product of calcium carbonate, K ... 

The solubility product constant, K p, for calcium carbonate at room temperature is approximately 3.0 X 10 . Calculate the solubility of CaCOj in grams per liter under these conditions. 

Calculate the conditional solubility product for CaCOsts). Ps CT.caXCr.cOg), where Cy.ca andCr.coj represent the total concentrations of these species in a solution with (a = 10 , pH = 8.7, the temperature = 25 C. Include ionic strength effects. Assume that the only soluble calcium species is Ca +. 

VJSi A 1.00-L solution saturated at 25 °C with calcium oxalate (CaC,04) contains 0.0061 g of CaC,04. Calculate the solubility-product constant for this salt at 25 °C. 

Not all salts exhibit a good aqueous solubility. A number of inorganic salts having a relatively low molecular weight and a low water solubility are listed in Table 18.6. Also the solubility product often is given (Table 18.7). This allows us to determine the effect of other ions in the solution on the solubility of a given substance, for example, when sodium carbonate is added to a solution of magnesium chloride. Also the reduction of the solubility of the poorly soluble calcium carbonate can be calculated when a certain amount of the readily soluble sodium carbonate or calcium chloride is added. This reduction in the solubility of, in this case, calcium carbonate is also known as the common ion effect. 

The mineral fluorite is calcium fluoride, Cap2. Calculate the solubility (in grams per liter) of calcium fluoride in water from the solubility product constant... 

The solubility product of biological apatite has been determined by suspending fresh defatted powder from cortical bone in an artificial solution containing inorganic ions at the concentrations present in an ultrafiltrate of normal serum. When equilibrium had been established the solution was removed and replaced by a fresh portion which was equilibrated, removed and analysed. Solutions obtained by repeating this procedure several times were found, after the first few changes, to have the same calcium and phosphate levels and these were used to calculate the solubility product for biological apatite. 

The ionic product for calcium and phosphate in human serum can therefore be calculated in the same units as for the solubility product. 

Exercise 2 The solubility product of calcium fluoride CaFa is = 4.0 x 10 ". Calculate its solubility in pure water. Neglect its intrinsic solubility. 

After filtration, addition of sodium sulphide to the clear solution effects the precipitation of the three metals, cobalt, nickel, and manganese, as sulphides. Digestion with the calculated quantity of ferric chloride oxidises the manganese sulphide to sulphate, which passes into solution. The residue consists of cobalt and nickel sulphides, which are washed and converted into their soluble sulphates by roasting. The sulphates are extracted with water, and converted into chlorides by addition of calcium chloride solution. Their separation is effected g.s follows The requisite fraction of the chloride solution is precipitated with milk of lime, and the insoluble hydroxides of nickel and cobalt thus obtained are oxidised to the black hydroxides by treatment with chlorine. The. washed precipitate is then introduced into the remainder of the chloride solution, and the whole is well stirred and heated, when the black hydrated oxide of nickel passes, into solution, displacing tlm Remainder of. the cobalt from the solution, into. the precipitate.. The final product is thus a suspension of hydrated peroxide.of cobalt,in p. solution of nickel chloride, from which idle cobalt precipitate is removed by filtration, washed, and ignited, to the black oxide. 

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