Calcium sulfate equation

Write the equation for the dissolving of calcium sulfate, CaSOt, and the solubility product expression. 

Will a precipitate form in either case In both The first step is to write the balanced equation for the reaction of calcium sulfate dissolving in water and then use the Equilibrium Law ... 

C04-0146. The largest single use of sulfuric acid is for the production of phosphate fertilizers. The acid reacts with calcium phosphate in a 2 1 mole ratio to give calcium sulfate and calcium dihydrogen phosphate. The mixture is crushed and spread on fields, where the salts dissolve in rain water. (Calcium phosphate, commonly found in phosphate rock, is too insoluble to be a direct source of phosphate for plants.) (a) Write a balanced equation for the reaction of sulfuric acid with calcium phosphate, (b) How many kilograms each of sulliiric acid and calcium phosphate are required to produce 50.0 kg of the calcium sulfate-dihydrogen phosphate mixture (c) How many moles of phosphate ion will this mixture provide ... 

The scaling tendency of the lime or limestone processes for flue gas desulfurization is highly dependent upon the supersaturation ratios of calcium sulfate and calcium sulfite, particularly calcium sulfate. The supersaturation ratios cannot be measured directly. They are determined by measuring experimentally the molalities of dissolved sulfur dioxide, sulfate, carbon dioxide, chloride, sodium and potassium, calcium, magnesium, and pH. Then by calculation, the appropriate activities are determined, and the supersaturation ratio is determined. Using the method outlined in Section IV, the concentrations of all ions and ion-pairs can be readily determined. The search variables are the molalities of bisulfite, bicarbonate, calcium, magnesium, and sulfate ions. The objective function is defined from the mass balance expressions for dissolved sulfur dioxide, sulfate, carbon dioxide, calcium, and magnesium. This equation is... 

All phosphorus fertilizers come from wet process phosphoric acid or directly from phosphate rock. Normal superphosphate, triple or concentrated superphosphate, and ammonium phosphate are the three common types used. Normal or ordinary superphosphate (NSP or OSP) is mostly monocalcium phosphate and calcium sulfate. It is made from phosphate rock and sulfuric acid and is equated to a 20% P2O5 content. It led the market until 1964. The production of normal superphosphate is similar to that for the manufacture of wet process phosphoric acid (Chapter 2, Section 3) except that there is only partial neutralization. Normal superphosphate is no longer used to any great extent. The following reaction is one example of an equation that represents this process. 

While the reverse solubility curve of calcium sulfate is often the main reason for scale deposition in fresh water boilers and in brackish water distillation, when the sea water is not chemically treated the cause is chemical rather than physical. Sea water contains bicarbonate ion. On heating, the bicarbonate ion reacts with water to form carbonate ion plus carbon dioxide, which tends to be evolved as a gas as shown in the equations... 

According to Hill [40], analyses of reaction products during the spray absorption drying shows that the reaction of the calcium hydroxide with the sulfur dioxide leads to calcium sulfate hemihydrate. The main reaction equation can be formulated as follows ... 

In the future, it seems likely that most processes that currently entail the discharge of SO2 will have to be adapted with the introduction of scrubbers . Two main methods can be employed for this either the reduction of SO2 to snllur using the Claus process or, alternatively, neutralization nsing milk of lime (equation 18) to give either calcium sulfite or, with complete oxidation, calcium sulfate (gypsum). 

In this equation the calcium sulfate is represented by separate hydrated ions because calcium sulfate dissolves in rainwater. Thus in areas bathed in rainwater the marble slowly dissolves away. 

One harmful effect of acid rain is the deterioration of structures and statues made of marble or limestone, both of which are essentially calcium carbonate. The reaction of calcium carbonate with sulfuric acid yields carbon dioxide, water, and calcium sulfate. Because calcium sulfate is marginally soluble in water, part of the object is washed away by the rain. Write a balanced chemical equation for the reaction of sulfuric acid with calcium carbonate. 

Appiying Concepts The processes used to remove metals from their ores usually involve a reduction process. For example, mercury may be obtained by roasting the ore mercury(II) sulfide with calcium oxide to produce mercury metal, calcium sulfide, and calcium sulfate. Write and balance the redox equation for this process. 

The dehydration and rehydration reactions of calcium sulfate dihydrate (gypsiun) are of considerable technological importance and have been the subject of many studies. On heating, CaS04.2H20 may yield the hemihydrate or the anhydrous salt and both the product formed and the kinetics of the reaction are markedly dependent upon the temperature and the water vapour pressure. At low temperatures (i.e. < 383 K) the process fits the Avrami-Erofeev equation (n = 2) [75]. The apparent activation energy for nucleation varies between 250 and 140 kJ mol in 4.6 and 17.0 Torr water v our pressure, respectively. Reactions yielding the anhydrous salt (< 10 Torr) and the hemihydrate ( (HjO) >17 Torr) proceeded by an interface mechanism, for which the values of E, were 80 to 90 kJ mol. At temperatures > 383 K the reaction was controlled by diffusion with E, = 40 to 50 kJ mol. ... 

Write balanced chemical equations for each of the following processes (a) Calcium phosphate reacts with sulfuric acid to produce calcium sulfate and phosphoric acid, (b) Calcium phosphate reacts with water containing dissolved carbon dioxide to produce calcium hydrogen carbonate and calcium hydrogen phosphate. 

Normal superphosphate or triple superphosphate (common commercial fertilizers) are cheap sources of water-soluble phosphate. Normal superphosphate is primarily a mixture of monocalcium phosphate and calcium sulfate (gypsum), while triple superphosphate is essentially all monocalcium phosphate. Monosodium phosphate was prepared from superphosphate by first leaching superphosphate with sea water until a saturated solution of monocalcium phosphate was obtained. Then the monocalcium phosphate solution in sea water was percolated through a column of Dowex 50 (strongly acidic type resin) in the sodium form. The effluent from the column was a solution of monosodium phosphate in sea water and the resin was converted to the calcium form as shown by Equation 6. 

The meaning of equation (32) is that the intensity of any peak hkl in the mixture / divided by the intensity of the same peak in the pure sample of phase a, la is given by the right hand side of the equation. The mixture and the pure phase measurements are carried out exactly in the same way. It is assumed that the phases have been identified prior to the intensity measurements, so their mass absorption coefficients may be calculated. As an example we will consider a mixture of LiCl and CaS04. The mass absorption coefficient of calcium sulfate is 77.37 cm /g. Let us assume that the mixture contains 10 weight percent CaS04. The mass absorption coefficient of the mixture is then... 

Although many sulfate salts are soluble in water, calcium sulfate is not (Table 7.1). Therefore, a solution of calcium chloride will react with sodium sulfate solution to produce a precipitate of calcium sulfate. The balanced equation is... 

Equations E23.2.8 and E23.2.9 can be solved using the appropriate initial and boundary conditions to compute the concentrations of A in the continuous and microphases as functions of time. However, these model equations depend on the average particle diameter, surface area, and volume of the microphase. Because they are constantly changing as more crystals nucleate and grow, complete knowledge of the crystallization kinetics of calcium sulfate is necessary to solve the equations. 

Initially, the hydration of C AjS progresses mainly according to equation (4.4) (section 4.1). However, if the dissolution rate of the calcium sulfate cannot keep pace with that of the C4A3S, the hydration may also progress partly according to reaction (4.3). Aluminum hydroxide is formed simultaneously. 

Calculation of Sulfuric Acid Requirement - Although the sulfuric add requirement for the production of phosphoric acid from any given rock is best obtained experimentally, it is sometimes necessary to calculate it from the chemical analysis of the rock. For a first approximation the sulfuric acid requirement may be equated to that required to combine with the caldum in the rock to form calcium sulfate. This calculated value is often dose enough for planning purposes. The requirement per tonne of P2O5 recovered should be adjusted according to the expected recovery. The overall recovery is seldom more than 94% if mechanical and sludge losses are included. 

The value G, the calcium sulfate produced, indicates the quantity of sludge, as well as the quantities of the consumed chemicals (sulfuric acid and calcium oxide). As the following equation shows, this quantity increases with increasing CODceii ... 

Solid calcium phosphate and aqueous sulfuric acid solution react to give calcium sulfate, which comes out of the solution as a solid. The other product is phosphoric acid, which remains in solution. Write a balanced equation for the reaction using complete formulas for the compounds with phase labels. 

Sample Problem E Aluminum sulfate and calcium hydroxide are used in a water-purification process. When added to water, they dissolve and react to produce two insoluble products, aluminum hydroxide and calcium sulfate. These products settle out, taking suspended solid impurities with them. Write a balanced chemical equation for the reaction. 

EDTA is also used to remove the calcium carbonate and sulfate scales that form in hot-water boilers and heaters. Calcium carbonate precipitates out when hard water is heated because the bicarbonate present in any naturally aerated water supply decomposes under the action of heat into carbonate, water, and carbon dioxide, as shown in Equation (6.15). (This reaction is the source of some of the very small bubbles that form on the sides of a beaker before water heated in it comes to a boil.) The carbonate is then available to be precipitated by calcium, magnesium, or iron cations that are often present in a natural water supply. This precipitation reaction is shown for calcium in Equation (6.16) ... 

Calcium sulfate is also used in a variety of commercial applications. The dihydrate, mined as gypsum, is used in Portland cement and for gypsum wallboard. When the dihydrate is heated, it yields the fine hemihydrate powder, CaS04 5H2O, known is plaster of paris. When plaster of pans is mixed with water, it makes a paste, or slurry, that hardens to form accurate molds. These reactions are summarized in Equation (13.28) ... 

To increase the solubility, phosphate rock can be treated with sulfuric acid, as shown in Equation (16.57). The resulting mixture, often called superphosphate, was the most common fertilizer of the 1940s. If phosphoric acid is used instead of sulfuric, as shown in Equation (16.58), the inert calcium sulfate of superphosphate is eliminated. This product is called triple superphosphate. 

Conversion of calcium oxide to calcium sulfate is limited by the plugging of the pores. A relation was reported between the conversion and porosity by Eq.2.26. That equation was written for a pure CaO particle. Eq.2.26 was modified for the presence of components other than CaO in the limestone. 

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