Oxidation-reduction potentials basic solutions

The oxidation-reduction potential or redox potential ( h) is a measure of the tendency of a solution to be oxidizing or reducing. Oxidation and reduction are basically electrical processes that are readily measiued by an electrode potential. All measurements are referred to die standard hydrogen electrode, the potential of which is taken as 0.00 V at 298 K, the H2 pressure as 101325 N/m (1 atm) and activities of H2 and as unity. When the half-cell reaction is written as an oxidation reaction ... 

Pentaralent neptunium is the most stable state in solution. It hydrolyzes only in basic solutions, disproportionates only at high acidity, and forms no polynuclear complexes. As shown by the oxidation-reduction potentials of Table 9.6, hexavalent neptunium is much less stable in solution than is hexavalent plutonium in fact, hexavalent neptunium is a strong oxidizing agent and is easily reduced in the presence of oxidizable substances, such as those present in ion-exchange and solvent extraction separations [K2]. 

Se032- + Fe304 + SHaO - Se042- + 3Fe(OH)2 These reactions spontaneously occur according to the oxidation-reduction potential in basic solution (7, 8). 

Figure 11.8 Oxidation states of nitrogen showing standard reduction potentials in volts (a) in acid solution at pH 0, and (b) in basic solution at pH 14.

The aluminum-air fuel cell is used as a reserve battery in remote locations. In this cell aluminum reacts with the oxygen in air in basic solution, (a) Write the oxidation and reduction half-reactions for this cell, (b) Calculate the standard cell potential. See Box 12.1. 

An LDH with the approximate stoichiometry Mgo.3Co(II)o.6Co(III)o.2(OH)2 (N03)o.2 H2O has been synthesized by oxidation of Co(ll) using an am-moniacal solution and hydrothermal treatments vmder various O2 N2 atmospheres [176]. The ammoniacal solution plays a number of roles in the synthesis. Firstly, it provides a basic medium. Secondly, it acts as hgand by forming a complex [CoCNHsle] ", which facihtates oxidation of Co to [CoCNHsle] because of the low standard reduction potential (E°) ... 

Practically in every general chemistry textbook, one can find a table presenting the Standard (Reduction) Potentials in aqueous solution at 25 °C, sometimes in two parts, indicating the reaction condition acidic solution and basic solution. In most cases, there is another table titled Standard Chemical Thermodynamic Properties (or Selected Thermodynamic Values). The former table is referred to in a chapter devoted to Electrochemistry (or Oxidation - Reduction Reactions), while a reference to the latter one can be found in a chapter dealing with Chemical Thermodynamics (or Chemical Equilibria). It is seldom indicated that the two types of tables contain redundant information since the standard potential values of a cell reaction ( n) can be calculated from the standard molar free (Gibbs) energy change (AG" for the same reaction with a simple relationship... 

This led to a reduction potential of 0.84V v. NHE at pH 3-6 for the couple S03 /HS03. The reduction potential of the S0q /S0o2 couple in basic solution is calculated [using pKa (HS0o H + S032 )=7.2] to be 0.63V. This change in potential helps explain why SO is oxidized by the same oxidant more readily than HS03. ... 

Civilization depends on the protection of metals, for most of them are unstable in normal environments unless they are protected by some kind of oxide film. The basic idea about the theory of corrosion is that the metal gets involved in a kind of local fuel cell in which it consumes itself. The partner to most of this self-dissolution is the deposition of hydrogen (favored in acid solutions) or the reduction of oxygen (favored in alkaline). Corrosion is measured in many ways, but the quick way in the laboratory is to move the potential a little bit away ( 5 mV) from the corrosion potential in both anodic and cathodic directions and measure the corresponding current. A simple equation takes the data from this type of measurement and produces the corrosion rate. 

For reductions in acid solution, oxidation potentials show that barium metal is a better reducing agent than calcium. The reverse is true in basic solution. Explain. 

The reduction potential for VOA 203 couple in the basic solution is -0.486V. The potential difference for oxidation of VO to V2O3 with oxygen is... 

---