Chlorine standard reduction potentials

Electrolysis of aqueous sodium chloride (brine) is an important industrial process for the production of chlorine and sodium hydroxide. In fact, this process is second only to the production of aluminum as a consumer cf electricity in the United States. Sodium is not produced in this process under normal circumstances because H20 is more easily reduced than Na+, as the standard reduction potentials show ... 

Chloramine, like chlorine, is an oxidizing biocide used for disinfection. Three species collectively make up chloramines, also known as combined chlorine monochloramine, NH Cl dichloramine, NHCl and nitrogen trichloride (trichloramine), NCI3. Of these, monochloramine has the highest standard reduction potential furthermore, it is less prone to impart chlorinous taste and odor to water like other forms of chloramine. As a result, monochloramine is preferred for disinfection applications. 

Based on standard reduction potentials, would chlorine gas be a reducing agent or an oxidizing agent Briefly discuss your answer. 

The standard reduction potential of O ig) to 02(g) is +2.07 V. Write a half-equation for this reduction in acid solution. How does ozone compare with chlorine gas, Cl2( ), as an oxidizing agent Of what practical, beneficial, environmental importance is the oxidiang abiUty of ozone Hint Refer to Chapter 11 if need be.)... 

The trends in the standard reduction potentials of the halogens are closely related to the uniqueness of fluorine. A quick inspection of Table 18.1 indicates that fluorine has the highest standard reduction potential (2.87 V) of the group and that chlorine is a distant second (1.36 V), with the rest of the values steadily decreasing from 1.07 V to 0.3 V after that. Note that the standard reduction potentials correspond to the half-reaction shown in Equation (18.6) ... 

Could chlorine be produced by the action of nitric acid on a chloride Support your answer by referring to standard reduction potentials. Write an equation as part of your answer. 

Many organometallic complexes react strongly with chlorine and bromine. Their standard reduction potentials are as follows ... 

Chlorine reactions may be classified broadly under two types (i) oxidation-reduction and (ii) substitution reactions. The standard electrode potential for Cr — V2CI2 + e in aqueous solution is -1.36 V. Some examples of both types are highlighted briefly below ... 

Passage of 1.0 mol of electrons (one faraday, 96,485 A s) will produce 1.0 mol of oxidation or reduction—in this case, 1.0 mol of Cl- converted to 0.5 mol of Cl2, and 1.0 mol of water reduced to 1.0 mol of OH- plus 0.5 mol of H2. Thermodynamically, the electrical potential required to do this is given by the difference in standard electrode potentials (Chapter 15 and Appendix D) for the anode and cathode processes, but there is also an additional voltage or overpotential that originates in kinetic barriers within these multistep gas-evolving electrode processes. The overpotential can be minimized by catalyzing the electrode reactions in the case of chlorine evolution, this can be done by coating the anode with ruthenium dioxide. 

By international agreement, the algebraic sign of E° for a half-cell is chosen to be the same as its electrical sign relative to the SHE. This means, in effect, that we must write the half-reactions with the electrons on the left-hand side in other words, E° values are taken to be reduction potentials. Consequently, a reagent such as chlorine that is more oxidizing than aqueous H+ (— H2) under standard conditions will have a positive E°... 

It was demonstrated that water electrolysis generates mixed oxidant systems. Oxidation-reduction potential (Hsu and Kao 2004) is not the best parameter for system characterisation. In general, the online analysis of generated species is an unsolved problem. Probably, not all electrolysis products are known. This can be seen in analysing the active and total chlorine concentration. The standard method uses DPD but the effect of other chemicals on the DPD method is one reason that active chlorine is sometimes incorrectly measured. Amperometric analysis and... 

These equations refer to one-electron reductions versus the standard hydrogen electrode. Substrates M with more positive reduction potentials for the couple M/ M are stronger oxidants than substrates with lower or negative E. Therefore, in this case, M is easier to reduce. Eor example, the couple Cl /Cr has a reduction potential E of 2.200 to 2.600 V, and therefore chloride ions can theoretically be oxidized in water to chlorine atoms by hydroxyl radicals with E( OH, H / H20) = 2.730 V, according to Eq. 6-3 ... 

Flow controllers set the rates of both streams, one being under flow-ratio control. In principle, either caustic soda or dilution water can be the master stream, with the other following it to maintain the ratio. Blending is controlled by a feedforward system, ultimately reset by the product concentration or density. Feedback from caustic concentration measurement (usually by density) could be used for final adjustment, but the concentration of the hypochlorite solution is the more important variable. The simple flow-ratio controller mentioned here can be replaced by a multi-stream version that allows use of other streams in addition to the principal 50% NaOH and dilution water. A cooler downstream of the mixing point removes the heat of dilution. The standard design is a titanium plate exchanger, which can also provide turbulence to complete the mixing process. Chlorine joins the diluted caustic in the reactor. Its rate of addition is controlled by an oxidation-reduction potential (ORP) instrument. The reaction mass recirculates from a collection tank around the system to reduce the increase of temperature across the reactor and to promote turbulence. The net production is removed from the tank, normally under level control. 

To reverse this half-reaction and bring about the oxidation of water, we need an applied potential difference of at least 0.82 V. Suppose the added salt is sodium chloride. When Cl ions are present at 1 mol-L 1 in water, is it possible that they, and not the water, will be oxidized From Table 12.1, the standard potential for the reduction of chlorine is Cl.36 V ... 

Several investigations have been made of the reduction of cobalt(II) to cobalt(O) in molten salt media. Eor a eutectic melt of LiCl-KCl at 450°C[10], a 1 1 NaCl-KCl melt at 450°C[11], and a MgCh-NaCl-KCl (50 30 20 mol%) mixture at 475 °C [12], the apparent standard potentials for the cobalt(II)-cobalt(0) couple have been deduced to be —1.207 V, — 1.277 V, and—1.046 V, respectively, each with respect to a chlorine-chloride ion reference electrode. 

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