A change in the oxidation state of two atoms determines every redox reaction. There is no redox reaction if the oxidation number does not change. Oxidation reduction processes may be traced back to the beginning of human history, from the first time humans encountered fire and employed it in their everyday lives, particularly during the Copper Bronze period of human development, around 4000–8000 years ago. People in that era benefited from the use of copper in their lives, they heated copper ores and coal in an oxidation reduction reaction in which copper ores are reduced to copper metal and coal is oxidized to carbon dioxide, and the Bronze age is also known for using clay in the production of pottery, in addition to copper, in this article we will have an inspection of redox reactions.
An inspection of redox reactions-
Now we will take a deeper look at what we mean by redox reactions, types of redox reactions and finally at balancing redox reactions and the oxidation number method.
Redox reactions-
Any chemical reaction in which the oxidation number of a participating chemical species changes is known as an oxidation-reduction reaction. The word refers to a broad range of processes. Many oxidation-reduction processes are as frequent and recognizable as fire, metal corrosion and dissolving, fruit browning, and essential life activities like breathing and photosynthesis.
The majority of oxidation-reduction (redox) reactions involve the transfer of oxygen, hydrogen, or electrons, with all three processes having two key characteristics:
(1) They are linked- A reciprocal reduction happens in every oxidation process.
(2) They entail a typical net chemical change, in which an atom or electron is transferred from one unit of matter to another.
Types of redox reactions-
1.Combination reaction- A chemical process in which two or more chemicals combine to generate a single new compound is known as a combination reaction. If one (or both) of the reactants are in the elemental state, the reaction is considered to be a redox reaction.
When both species (A & B) or either of the species (A & B) are present in their elemental form, this sort of reaction is referred to as a redox reaction. The breakdown process is the polar opposite of this sort of redox reaction (oxidation and reduction).
2Na(s)+Cl2(g)→2NaCl(s)
2.Decomposition reaction- process occurs when a complex is broken down into two or more simple components. The reaction of decomposition is the polar opposite of the reaction of combination. Decomposition reactions aren’t all redox reactions.
If at least one of the decomposition process’s products is in the elemental form, the reaction is called a redox reaction.
2 H2O2→ 2 H2O + O
3.Displacement reaction- A compound’s atom (or) ion is replaced by an atom (or) ion from another element or compound.
Mg(s)+CuSO4 (aq)⟶MgSO4 (aq)+Cu(s)
4.Disproportionation reaction- This is a process that involves the oxidation and reduction of the same element. When one of the reactive elements has at least three oxidation states, such reactions occur.
Furthermore, the element in the reactive molecule must be in the intermediate oxidation state, while oxidation and reduction need the lower and higher oxidation states, respectively. The breakdown of hydrogen peroxide, in which oxygen species are disproportionated, is a frequent example of such a process.
Mn2O3 becoming Mn2+ and MnO2
Balancing redox reactions oxidation number method-
First, we will take a look at what we mean by balanced equation- The reactants and products of a chemical reaction are listed in an imbalanced chemical equation, but the quantities necessary to meet the conservation of mass are not stated. For example, in terms of mass Fe2O3 + C → Fe + CO2, this equation for the interaction between iron oxide and carbon to generate iron and carbon dioxide is imbalanced.
Because there are no ions on both sides of the equation, the charge is balanced (net neutral charge).
On the reactants side of the equation (to the left of the arrow), there are two iron atoms, but only one on the products side (right of the arrow). You can see the equation isn’t balanced even if you don’t count the other atoms’ amounts.
On both the left and right sides of the arrow, the purpose of balancing the equation is to have the same number of each kind of atom. This is accomplished by altering the compound coefficients (numbers placed in front of compound formulas). Subscripts (small numbers to the right of certain atoms, such as iron and oxygen in this case) are never altered. The chemical identification of the compound would be altered if the subscripts were changed.
2 Fe2O3 + 3 C → 4 Fe + 3 CO2 is the balanced equation.
Now will look at oxidation number method-
HNO₃ + H₃AsO₃(aq) → NO(g) + H₃AsO₄(aq) + H₂O(l)
- Determine each atom’s oxidation number.
H = +1; N = +5; O = -2; As = +3 on the left.
N = +2; O = -2; H = +1; As = +5 on the right side.
2.For each atom that changes, calculate the change in oxidation number.
As: +3 +5; Change = +2 N: +5 +2; Change = -3 As: +3 +5; Change = +2
3.Make the overall oxidation number rise equal to the total oxidation number decrease.
For every three atoms of As, we require two atoms of N. We have total changes of -6 and +6 as a result of this.
4.Place these values in front of the formulae that include those atoms as coefficients.
2HNO₃ + 3H₃AsO₃(aq) → 2NO(g) + 3H₃AsO₄(aq) + H₂O(l)
5.Balance the remaining atoms, excluding H and O.
6.Done
Conclusion-
In this article we read about what do we mean by redox reaction, its types and the oxidation number balancing method. Redox reactions are significant since they are the primary sources of energy on our planet, both natural and man-made. Large amounts of energy are generally released when molecules are oxidized by removing hydrogen or combining with oxygen. Photosynthesis, respiration, combustion, and corrosion or rusting are just a few of the essential operations of life that rely on redox reactions.