Bleaching, 194 redox reactions

Redox reactions occur in the reduction of ores (metal oxides) into pure metals and the corrosion (oxidation) of pure metals in the presence of oxygen and water. Rusting iron, 4Fe + 30, + 611,0 —> 4Fe(OH), is a good example of metal oxidation. Strong oxidizing agents can be used as antiseptics (hydrogen peroxide, Fd,0,) or bleaches (sodium hypochlorite, NaOCl). 

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine CIO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S203 I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S406. In this analysis, potassium iodide was added in excess to 5.00 ml of bleach d = 1.00 g/cm3). If 25.00 mL of 0.0700 MNa2S203 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaCIO in the bleach ... 

Household ammonia should never be mixed with chlorine bleach, because a redox reaction occurs that generates toxic chlorine gas and hydrazine NH3 + OCl —> CI2 + N2 H4 (unbalanced) Balance this equation. 

Dark hair can be bleached by a redox reaction with hydrogen peroxide. 

Especially important are the radical-redox reactions by which transition metals promote free radical generation by catalyzing the decomposition of the peroxides formed during bleaching. This faster free radical generation results in higher oxidation rates and a more extensive depolymerization of the cellulose. 

However, given the presence of these complexing agents in oxygen bleaching, what is required to prevent catalyzed oxidation is a stronger, stable complex that will not permit participation of the transition metals in the radical-redox reactions. This appears to be the most plausible role to ascribe to magnesium. 

Oxidation-reduction reactions, also known as redox reactions, are chemical processes in which electrons are transferred from one atom, ion, or molecule to another. Explosions, fires, batteries, and even our own bodies are powered by oxidation-reduction reactions. When iron rusts or colored paper bleaches in the sun, oxidation-reduction has taken place. 

Say Cheese Redox in Photography Having a Blast Redox in a Blast Furnace Redox in Bleaching Processes Corrosion of Metals Silver Tarnish A Redox Reaction Chemiluminescence It s Cool Biochemical Redox Processes MiniLab 16.2 Testing for Alcohol by Redox... 

Sodium chlorate, NaC103, which is used to bleach paper, is made in the following reactions. Determine the oxidation number for each atom in the equations and identify whether each reaction is a redox reaction or not. If a reaction is redox, identify what is oxidized and what is reduced. 

Whereas acid-base reactions can be characterized as proton-transfer processes, the class of reactions called oxidation-reduction, or redox, reactions are considered electron-transfer reactions. Oxidation-reduction reactions are very much a part of the world around ns. They range from the burning of fossil fuels to the action of household bleach. Additionally, most metallic and nomnetaUic elements are obtained from their ores by the process of oxidation or reduction. 

Bleaches use redox reactions to remove color from material (see Chapter 9 for a discussion of redox reactions). Most bleaches are oxidizing scents. The most common bleach used in the home is a 5 percent solution of sodium hypochlorite. This type of bleach is produced by bubbling chlorine gas through a sodium hydroxide solution ... 

Co 7Co02) and metal ion/metal systems (Ag7Ag) can be used [4]. In the former system, metal ions are oxidized to colored metal oxides by holes generated in the valence band of the photo-irradiated semiconductor and bleached by electrochemical reduction of the oxide. In the latter, metal ions are reduced to colored metal particles by photoexcited electrons in the conduction band. A system with Prussian white/ Prussian blue is also used. Prussian white on Ti02 is oxidized to Prussian blue by UV irradiation [5]. Redox reactions of conducting polymers such as... 

Reactions involving the transfer of electrons are called oxidation-reduction reactions or redox reactions. Redox reactions are responsible for the rusting of iron, the bleaching of hair, and the production of electricity in batteries. Many redox reactions involve the reaction of a substance with oxygen. 

Oxidation and Reduction Redox reactions are common in nature, in industry, and in many everyday processes. Batteries use redox reactions to generate electrical current. Our bodies use redox reactions to obtain energy from glucose. In addition, the bleaching of hair, the rusting of iron, and the electroplating of metals all involve redox reactions. 

The effect of pycocyanine (PC ) observed supports the suggested mechanism. PC" is present in the aqueous phase and is reduced by DQ. The neutral PC produced can enter the micelle and reduce in turn chl-a ". Thus, the fraction of chl-a initially removed from the sphere of observation is replenished rapidly via this sequence of redox reactions. Hence, no long-tem bleaching of chl-a is expected to occur as indeed is observed. Thus the lifetime of intermediates produced by the photoredox event could be prolonged by several orders of magnitude through en loyment of suitable micellar systems instead of... 

The bleaching of hair involves a redox reaction in which melanin— the main pigment in hair— is oxidized. 

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