Photosynthesis 157 electron gain

Plants use the process of photosynthesis to obtain energy. During photosynthesis, electrons are moved from molecule to molecule. In this laboratory exercise, we will use a chemical dye called DPIR The DPIP dye turns from a blue color to clear when it gains electrons.The amount of color lost is measured in a spectrophotometer as an increase in the percentage of transmittance. 

They are the basis of many products and processes, from batteries to photosynthesis and respiration. You know redox reactions involve an oxidation half-reaction in which electrons are lost and a reduction half-reaction in which electrons are gained. In order to use the chemistry of redox reactions, we need to know about the tendency of the ions involved in the half-reactions to gain electrons. This tendency is called the reduction potential. Tables of standard reduction potentials exist that provide quantitative information on electron movement in redox half-reactions. In this lab, you will use reduction potentials combined with gravimetric analysis to determine oxidation numbers of the involved substances. 

Natural photosynthesis provides the most dramatic demonstration of the potential hidden in this basic photoreaction. In (bacterial) photosynthesis a chlorophyll-dimer (BC)2—the special pair —receives the radiation energy and thereby gains the energy required to enable it to transfer an electron to a pheophytin moiety (BP), an act occurring within 2-3 picoseconds (Martin et al. 1986) even at very low temperatures. Subsequently the electron is transferred to a quinone acceptor (MQ), which once again occurs (Holten et al. 1978) on a very short time scale of about 230 ps. 

Abstract Photoredox catalysis by well-known nithenium(II) polypyridine complexes is a versatile tool for redox reactions in synthetic organic chemistry, because they can effectively catalyze single-electron-transfer (SET) processes by irradiation with visible light. These favorable properties of the catalysts provide a new strategy for efficient and selective radical reactions. Salts of tris(2,2 -bipyridine)mthenium (II), [Ru(bpy)3], were first reported in 1936. Since then, anumber of works related to artificial photosynthesis and photofunctional materials have been reported, but only limited efforts had been devoted to synthetic organic chemistry. Remarkably, since 2008, this photocatalytic system has gained importance in redox reactions. In this chapter, we will present a concise review of seminal works on ruthenium photoredox catalysis around 2008, which will be followed by our recent research topics on trifluoromethylation of alkenes by photoredox catalysis. 

Photosynthesis may also be considered as a coupled redox reaction, in which it is involved in the gain or loss of electrons as follows ... 

Reduction is a process, which either involves the gain of electrons/hydrogen or loss of oxygen/decrease in oxidation state. An oxidation-reduction reaction occurs in our everyday life and is very vital for some of the basic functions of life. Some examples include photosynthesis, respiration, combustion, corrosion and rusting. 

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