Strontium redox reactions

C04-0102. Write the balanced redox reactions for the formation of each of the following oxides from the reaction of molecular oxygen with pure metal (a) strontium oxide (b) chromium(III) oxide (c) tin(IV) oxide. 

Fig. 10-26. Energy diagram for a cell of photoelectrolytic decomposition of water consisting of a platinum cathode and an n-type semiconductor anode of strontium titanate of which the Fermi level at the flat band potential is higher than the Fermi level of hydrogen redox reaction (snao > epM+zHj) ) he = electron energy level referred to the normal hydrogen electrode ri = anodic overvoltage (positive) of hole transfer across an n-type anode interface t = cathodic overvoltage (negative) of electron transfer across a metallic cathode interface.

At intermediate depths (down to 500 m) groundwaters rapidly increase in concentration primarily by the addition of SO4 and Cl. The concentration of bicarbonate ions decreases because of the precipitation of mineral phases such as calcite. Local variations in chemistry and anions may be due to a variety of rock-water interactions or local processes that result in Na-SO4, Na-HC03, and Mg-S04 type waters. The pH begins to rise in this zone and oxygenconsuming reactions and redox mineral controls tend to lower the Eh. The brackish and saline waters found at these intermediate depths have longer residence times. Deep saline waters and brines occur in most locations below depths of 500 m. These fluids are Ca-Na-Cl or Na-Ca-Cl in composition and can have total dissolved loads up to 350 g L. Minor elements such as bromide and strontium can here be thousands of milligrams per liter. 

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