The half-reaction method is also termed, as half-cell reaction is associated with either process of oxidation or reduction associated with the components of the redox reaction. Redox reaction involves a process of transference of electrons between the two chemical components involved in a particular set of reactions. The transference of electrons is noticed from the oxidation states of the participant chemical components. In this process of chemical reaction, the ability to the reduction of chemical compounds by gaining electrons is termed their particular reduction potential. This potential of reduction associated with the gaining of electrons is measured by volts or mini-volts. Half-cell potential is the development of potential at each electrode of half-cell
Reduction potential
The reduction potential of the chemical components involved in a reaction is associated with the process of transference of electrons and thereby, undergoing a process of reduction. In chemistry, the half-reaction method potentially is often measured against “SHE” under the standard condition which is determined as the standard potential state of the electrode for a particular half-reaction. An example of the standard “reduction potential”, for the reaction: “Zn2+(aq) + 2e− → Zn(s) is −0.76 V”, denotes that the potential standard state of the electrode in this reaction occurring at the anode to oxidize Zinc (Zn), to “Zn2+” which is often known as the redox couple, “Zn/Zn2+”. Here, for this redox couple, the oxidation result is “Zn/Zn2+ = − (−0.76 V) = 0.76 V” by subtracting “E° anode from E° cathode to obtain E° cell: 0 − (−0.76 V) = 0.76 V”. Here, the consequent values of E° are kept independent of the coefficients of “stoichiometric” in reduction potential for half-reaction. Coefficients here are mainly used to obtain a balanced result of the entire reaction, which will not be affecting cell potential value.
Reduction potential table
The reduction potential table usually denotes E° for the nominated “reduction reactions”. Reduction potential is determined as the measure that is associated with the acquisition and loss of electrons of the chemical components involved in a chemical reaction. For an example, for the chemical reaction:
[OF2 (g) + 2 H+ (aq) + 4 e– → H2O (l) + 2 F–(aq)]
OF (gas) compound combines with two protons and four electrons then as a result, water (H2O) and Fluoride (F) are obtained.
Reduction potential table | |
Reduction half-reaction(Acid solution) | Standard potential, E° (V) |
[OF2(g) + 2 H+(aq) + 4 e– → H2O(l) + 2 F–(aq)] | 2.1 |
[MnO4–(aq ) + 4 H+(aq) + 3 e–→ MnO2(s) + 2 H2O(l)] | 1.70 |
[S2O82- (aq) + 2 e–→ 2 SO42-(aq)] | 2.01 |
[Au3+(aq) + 3 e–→ Au(s)] | 1.52 |
[Au3+(aq) + 2 e–→ Au+(aq)] | 1.36 |
Reduction half-reaction(Basic solution) | Standard potential, E° (V) |
[2 H2O(l) + 2 e–→ H2(g) + 2 OH–(aq)] | -0.828 |
[NO3–(aq ) + H2O(l) + 2 e–→ NO2–(aq) +2 OH–(aq )] | 0.01 |
[O2(g) + 2 H2O(l) + 4 e–→ 4 OH–(aq)] | 0.401 |
Half-reaction method
The way by which the redox reaction is balanced is known as the method of “half-reaction”. The half-reaction process also involves the breakdown of the entire equation into a reduction and oxidation part. Here, some reducing agents like hydrogen gas, and carbon compounds like coal and coke, which are referred to as important antioxidants absorbing vitamin E and “ascorbic acid” are incorporated in the half-reaction methods.
Standard Reduction Potential
The tendency to measure oxidation and reduction states of the chemical components, which are opposed to being reduced. In order to calculate the “standard reduction potential”, SRP is needed to be subtracted from the chemical reaction that occurs at the “anode” from the SRP for the reaction that occurs at the “cathode”. As an example of the Standard Reduction Potential (SRP): “AC++ Ce–→A”, the SRP of copper, “E°=+0.340V” for the reaction is: “Cu2++2e–→Cu”.
Conclusion
In the process of a chemical reaction, the involved chemical components undergo certain changes. The changes associated with the transference of electrons between the reactants are termed redox reactions. In this chemical reaction, the change in states of the components involved is noticed from their particular state of oxidation and reduction. The state of reduction of the components involved by the gaining of electrons is noted by their respective reduction potential. This transference of electrons in a chemical reaction is termed a redox reaction. The process of oxidation and reduction of the chemical components in a redox reaction is termed a half-reaction.