Before understanding what are reducing agents, you need to know what reduction and oxidation is? Generally, students get confused in redox reactions that which element is getting reduced and which is getting oxidized. So, we are explaining oxidation and reduction first in brief here.
Reduction is loss of oxygen atoms and gain of electrons and hydrogen. While oxidation is gain of oxygen and loss of electrons and hydrogen. Thus, we can say when an element gets oxidized, its oxidation state increases while in reduction it decreases. Same thing is explained in concise way in the table given below –
The reactions in which oxidation and reduction both take place are called redox reactions.
Examples of Oxidation and Reduction –
Reaction of copper with silver nitrate is an example of redox reaction. The reaction is given below showing oxidation and reduction. Image will be uploaded soon.
Reaction between magnesium and oxygen is an example of redox reaction. The reaction is given below showing oxidation and reduction – Image will be uploaded soon.
Reaction between iron and oxygen – Image will be uploaded soon.
Reaction between iron oxide and carbon monoxide – Image will be uploaded soon.
Reaction of copper oxide with hydrogen – Image will be uploaded soon.
Reaction of iron oxide with hydrogen – Image will be uploaded soon.
Reducing agent is an element (or compound) that –
Loses its electron/s to an electron recipient group and
Itself gets oxidized in a redox chemical reaction.
Thus, reducing agent reduces others while itself gets oxidized by losing electrons. As reducing agents lose electrons so generally, they possess low electronegativity and very small ionization energies. S-block metals generally work as good reducing agents. It is also called reductant or reducers.
Let’s understand it by an example of redox reaction – Image will be uploaded soon.
In the above reaction iron is losing 2 electrons thus, acting as a reducing agent. Oxidation state of iron as a reactant is 0 while +2 as a product in the reaction. Thus, the oxidation state of iron is increasing, so oxidation is taking place. While another reactant copper is gaining two electrons and working as an oxidizing agent. The oxidation state of copper is +2 as reactant in the reaction while 0 as product so reduction is taking place. Thus, iron is acting as a reducing agent but getting oxidized itself while copper is acting as an oxidizing agent but reduced.
Following are the common reducing agents –
Lithium aluminum hydride (LiAlH4)
Sodium lead alloy
Some examples of redox reactions are given below in which reducing and oxidizing agents have been shown for your better understanding –
Reaction of Zinc and Copper – Image will be uploaded soon.
Reaction of Ammonia and Oxygen – Image will be uploaded soon.
Reaction of Copper Sulfate with Zinc – Image will be uploaded soon.
As you can see, the oxidation state of zinc is increasing so it's getting oxidized. Thus, zinc is working as a reducing agent in the above reaction. While copper sulfate is working as an oxidizing agent as the oxidation state of copper is decreasing.
Reaction of Hydrogen Sulfide with Chlorine – Image will be uploaded soon.
As oxidation state of sulfur is increasing (-2 🡪 0) so it is working as reducing agent in the reaction while oxidation state of chlorine is decreasing so it is working as oxidizing agent.
Strong reducing agents are electropositive elements which can lose electrons easily in the chemical reactions. Strong reducing agents are weak oxidizing agents. Sodium, hydrogen, and lithium are examples of strong oxidizing agents. While weak reducing agents cannot lose electrons easily. Fluorine, chlorine, iron etc. are weak reducing agents. We can know the strength of reducing agents by electrochemical series as well. As we move upwards from hydrogen in the electrochemical series then the strength of reducing agents decreases. While if we move downwards from hydrogen then the strength of reducing agents increases. (image will be uploaded soon).
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