Strontium sulphate

Self regulating chromium The self-regulating chromium solutions were introduced to eliminate the need for maintaining the correct catalyst concentration by periodic analysis they depend on the addition of a sparingly soluble sulphate to the bath which supplies the correct amount of SO 4 automatically. Initially strontium sulphate (solubility approx. l-75g/l at 30°C and 21 g/1 at 40°C) was employed for this purpose. The strontium sulphate forms a layer on the bottom of the bath, which must be stirred from, time to time. A bath with a CrO, concentration of 250 g/1 would have a catalyst content of l 52g/l SrS04 and 4-35 g/1 of KjSiF. Potassium dichromate and strontium chromate have also found application as additives for the control of the saturation solubility of the catalyst. 

Strontium sulphate (celestite) Exoskeletons of a few marine organisms... 

Todd, A. C. and M. Yuan, 1990, Barium and strontium sulphate solid-solution formation in relation to North Sea scaling problems. SPE Production Engineering 5, 279-285. 

Precipitation of Sparingly Soluble Salts. Pom 2-3 ml of barium chloride, strontium chloride, and calcium chloride solutions into three test tubes. Add a sodium sulphate solution to the first tube, a saturated calcium sulphate solution to the second one, and a saturated strontium sulphate solution to the third one. Write the equations of the chemical reactions in the molecular and net ionic forms. 

In some of the furnace reactions in which none of the substances are melted, as, for example, in the reduction of strontium sulphate to strontium sulphide by means of charcoal (see Preparation 20), the process probably takes place by virtue of a certain amount of gas which is continuously regenerated. A little... 

Strontium Hydroxide from Strontium Sulphate, Sr(0H)2-8H20... 

Strontium Chloride from Strontium Sulphate, SrCl2-6H20... 

The method consists in first converting the sulphate into the carbonate by boiling it with a concentrated solution of sodium carbonate, and then dissolving the carbonate in hydrochloric acid, thereby yielding a solution of the chloride. The conversion of solid strontium sulphate into solid strontium carbonate furnishes an interesting illustration of the solubility product principle, for the solubility of these two salts in pure water is as follows ... 

Strontium sulphate would dissolve in the solution of sodium carbonate in the same manner as it would in pure water until it had saturated the solution, and its solubility product, which is equal to 0.0006 X 0.0006, was reached, but for the fact that long before this could occur the solution would be supersaturated with respect to strontium carbonate, the solubility product of which is only equal to 0.00007 X 0.00007. Thus strontium carbonate is precipitated continuously as strontium sulphate dissolves and since the solution cannot become saturated with the latter as long as a large excess of carbonate ions is present, the solid salt finally remaining will consist entirely of strontium carbonate, provided a sufficient amount of sodium carbonate were employed. The reaction which takes place is, however, reversible, SrSO + Na2C03 SrCOj + NasSO, and, if strontium carbonate were boiled with a solution of sodium sulphate, the solid would change into sulphate until carbonate ions had accumulated in the solution to such an extent as to make the concentration ratio [C03 ] [SO4 ] = 1 74. When this ratio prevails, both solids are in equilibrium with the solution and no change takes place in either direction. 

Explain why strontium carbonate, which is less soluble in pure water than strontium sulphate, should dissolve readily in dilute acids, while the latter salt will dissolve scarcely any more in acids than in pure water. 

The mineral witherite often contains barium sulphate as an impurity. State what changes this substance would undergo during the above process. How could barium hydroxide be prepared from barium sulphide (Compare preparation of strontium hydroxide from strontium sulphate, page 194.)... 

Sodium nitrate (crude) P. 1 Sodium potassium tartrate P. 29 Sodium silicate P. 41 Sodium sulphantimonate P. 58 Sodium sulphide P. 57 Strontium sulphate (celestite) P. 20, 21... 

Cobalt Thiosulphate, CoS203.6H20, is prepared3 by mixing equivalent solutions of cobalt sulphate and strontium thiosulphate. After filtering off the insoluble strontium sulphate, the solution is concentrated over sulphuric acid, when a deliquescent, dark red crystalline mass separates out. 

Nickel Thiosulphate, NiS203.6H20. is readily obtained by mixing equivalent solutions of nickel sulphate and strontium thiosulphate. Insoluble strontium sulphate is filtered off, and the clear solution upon evaporation yields green triclinie prisms of nickel thiosulphate.4... 

Saturated calcium sulphate solution immediate white precipitate of barium sulphate. A similar phenomenon occurs if saturated strontium sulphate reagent is used. 

The explanation of these reactions is as follows of the three alkaline earth sulphates barium sulphate is the least soluble. In the solutions of saturated calcium or strontium sulphate the concentration of sulphate ions is high enough to cause precipitation with larger amounts of barium, because the product of ion concentrations exceeds the value of the solubility product ... 

Dilute sulphuric acid white precipitate of strontium sulphate ... 

Strontium carbonate is less soluble than strontium sulphate (solubility 5-9 mg SrC03 1, Ks = 1-6 x 10-9 at room temperature). 

Saturated calcium sulphate solution white precipitate of strontium sulphate, formed slowly in the cold but more rapidly on boiling (distinction from barium). 

The precipitate is appreciably soluble in water (0 61 g Ca2+, 2 06 g CaS04 or 2-61 g CaS04.2H20 t-1, Ks = 2 3 x 10-4) that is more soluble than barium or strontium sulphate. In the presence of ethanol the solubility is much less. 

Strontium sulphate (saturated). Shake 0-1 g strontium sulphate, SrS04, with... 

Lithium sulphate forms no double salt with barium or strontium sulphate, and in this respect it differs from the other alkali sulphates which form compounds of the types M S04.3Ma S04 M"S04,M2 S04 2M"S04.M2 S04. For example,... 

Manufacture. Strontium carbonate occurs naturally as a strontium ore, but the production is not large. Celestine(consisting mainly of SrSO and containing Ca and Ba) is heated with sodium carbonate to form a melt, and the product is then washed with water to remove the strontium sulphate. 

Ammonium perchlorate Strontium sulphate Calcium sulphate Sodium sulphate Barium sulphate... 

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