WHERE DOES PHOTOSYNTHESIS OCCUR?

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Apart from the food they manufacture, plants also need carbon, hydrogen and oxygen to survive. Water absorbed from the soil provides the hydrogen and oxygen. During photosynthesis, carbon and water are used to synthesize food. They also need nitrate to make amino acids (Amino acid an ingredient for making protein). In addition to that, they need magnesium to make chlorophyll.

In this lesson, we shall learn more about how plants manufacture food (photosynthesis), and learn more about the conditions that must be present for this to happen.

PHOTOSYNTHESIS HAS TWO MAIN REACTIONS

Hydrogen is one of two natural elements that combine to make water. Hydrogen is not an energy source, but an energy carrier because it takes a great deal of energy to extract it from water. It is useful as a compact energy source in fuel cells and batteries. Many companies are working hard to develop technologies that can efficiently exploit the potential of hydrogen energy. This page lists articles about hydrogen fuel as an alternative energy source.


This reaction can be summarised in the word equation:

Carbon dioxide + water  glucose + oxygen

This Tuesday we had a unique opportunity to preview the Vancouver International Auto Show. This year’s show features a wide variety of electric, hydrogen and hybrid-electric vehicles. We took full


T2 - Accounts of Chemical Research

N2 - Natural photosynthesis uses sunlight to drive the conversion of energy-poor molecules (H2O, CO2) to energyrich ones (O2, (CH2O)n). Scientists are working hard to develop efficient artificial photosynthetic systems toward the "Holy Grail" of solar-driven water splitting. High on the list of challenges is the discovery of molecules that efficiently catalyze the reduction of protons to H2. In this Account, we report on one promising class of molecules: cobalt complexes with diglyoxime ligands (cobaloximes). Chemical, electrochemical, and photochemical methods all have been utilized to explore proton reduction catalysis by cobaloxime complexes. Reduction of a CoII-diglyoxime generates a CoI species that reacts with a proton source to produce a CoIII-hydride. Then, in a homolytic pathway, two Co IIIhydrides react in a bimolecular step to eliminate H2. Alternatively, in a heterolytic pathway, protonation of the Co III-hydride produces H2 and CoIII. A thermodynamic analysis of H2 evolution pathways sheds new light on the barriers and driving forces of the elementary reaction steps involved in proton reduction by CoI-diglyoximes. In combination with experimental results, this analysis shows that the barriers to H2 evolution along the heterolytic pathway are, in most cases, substantially greater than those of the homolytic route. In particular, a formidable barrier is associated with CoIII-diglyoxime formation along the heterolytic pathway. Our investigations of cobaloxime-catalyzed H2 evolution, coupled with the thermodynamic preference for a homolytic route, suggest that the rate-limiting step is associated with formation of the hydride. An efficient water splitting device may require the tethering of catalysts to an electrode surface in a fashion that does not inhibit association of CoIII-hydrides.

JF - Accounts of Chemical Research

When researchers arrive at a particular after lots of experimentation they already have used up lots of resources in terms of money, man, material and time. Now scientists are

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Environmentalists are continuously searching for green and clean fuel. Until now they have been putting a lot of energy and talent into hydrogen fuels because when hydrogen is burned,