Water-splitting

Oxygen is a good oxidizing agent, but so is chlorine. What does this tell you about their relative positions in the periodic table  

Was this your answeT Chlorine and oxygen must lie in the same area of the periodic table. Both have strong effective nuclear charges, and both are strong oxidizing agents. 

Rust itself is not harmful to the iron structures on which it forms. It is the loss of metallic iron that ruins the structural integrity. 

A piece of iron metal begins to rust when iron atoms lose electrons to form Fe2+ ions. These electrons are lost to oxygen atoms, which are thereby reduced to hydroxide ions, OH-. One region of the piece of iron behaves as the anode while another region behaves as the cathode. Rust forms only in the region of the anode, where iron atoms lose electrons. The loss of elemental iron in this region causes a hole to form in the metal. The formation of rust, however, is not as much of a problem as is the loss of iron atoms, a loss that results in a decrease in structural integrity. 

The galvanized nail (bottom) is protected from rusting by the sacrificial oxidation of zinc. 

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Rogner, M., Boekema, E. J., and Barber, J., 1996. How does photosystem 2 split water The structural basis of energy conversion. Trends in Biochemical Sciences 21 44—49. 

Although Ru(bipy)2+ alone will not split water into hydrogen and oxygen, it has been accomplished with Ru(bipy)2+ using various catalysts or radical carriers. Perhaps the most studied system for the photoreduction of water involves using methyl viologen as the quencher, EDTA as an electron donor (decomposed in the reaction) and colloidal platinum as a redox catalyst (Figure 1.19). 

H2 0(/) + Energy -> 2 H2 (g) + O2 (g) Sunlight may be the future source of energy for splitting water, but this remains a major technological challenge. 

Explain why photocatalysts based on Ti02 have limited efficiency for splitting water. 

From there, the reaction flow either leaves the total system to be quenched or, more commonly, enters the next plate which contains a delay loop, a spiral channel [56]. Leaving that plate, the streams flow to the last structured plate containing a bifurcation-mini mixer unit. The streams are distributed in multiple streams and contacted with a likewise split water stream. This leads to fast dilution, e.g., of a concentrated sulfuric acid stream, and rapidly cools the reaction stream. The reaction is quenched more or less initially. The final plate is unstructured and acts as a cover plate with holes for liquid withdrawal (Figure 4.28). 

E-beam (using high-energy electrons to split water molecules into free radicals). 

The problem of ion transfer across the interface has been treated in detail by Sato,26,27 Scully,28 and also Valand and Heus-ler,29 following the general theory of Vetter.30 Valand and Heusler assumed the same type of activation-controlled charge transfer kinetics, except that the dominant charge here is that on the O2-ions (or OH- ions) obtained by splitting water at the interface. The electrochemical double layer here is of the usual type for aqueous systems and the equilibrium p.d. is determined by the main charge transfer reaction... 

Sun, X., Liu, H., Dong, J., Wei, J., and Zhang, Y. (2010) Preparation and characterization of Ce/N-codoped Ti02 particles for production of H2 by photocatalytic splitting water under visible light. Catalysis Letters, 135 (3-4), 219-225. 

The discussions in Sections 7.1 through 7.4 paint a picture of the difficult ordeal of generating hydrogen and oxygen by splitting water using available materials and the universally available sunlight in a stable and efficient manner. 

It is possible to split water by irradiating ultra sound wave (USW) with 50 - 300 [kHz] onto water [15]. This phenomenon is called water sonolysis. If the cavitation bubble in water expands to the size with radius rc ( 10"4 m), and then implodes to a smaller bubble with radius r0 ( 10 6 m), the temperature inside the smaller bubble will rise to Tn given by... 

A third area of hydrogen from biomass is metabolic processing to split water via photosynthesis or to perform the shift reaction by photo biological organisms. This is an area of long-term research. 

Hydrolysis means to split water, the word coming from the two Greek roots hydro meaning water, and lysis meaning to cleave or split. ... 

In the charge, or electrolysis mode, the process splits water into hydrogen and oxygen and can produce hydrogen directly without mechanical compression. Water enters the cell and is split at the surface of the membrane to form protons, electrons and gaseous oxygen. 

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