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Identifying Redox Reactions Study Guide

Redox reactions are oxidation-reduction chemical processes in which the oxidation states of the reactant changes.

INTRODUCTION

A new object made of iron is initially grey, but it will develop a reddish appearance if left in the open for a long time. This is due to the oxidation of iron, also known as rusting. This is a typical example of the redox reaction that we see in our everyday lives. So, are you wondering what a redox reaction is? 🤔

Corrosion - Redox Reaction Source

REDOX REACTIONS:

Redox reactions are oxidation-reduction chemical processes in which the oxidation states of the reactant changes. (The degree of oxidation for an atom in a chemical compound is indicated by its oxidation state, which is the imaginary charge that an atom would have if all links to atoms of various elements were entirely ionic.)

  • The loss of electrons or a rise in the oxidation state of an atom, an ion, or specific atoms in a molecule is referred to as oxidation.
  • The gaining of electrons or a drop in the oxidation state of an atom, an ion, or specific atoms in a molecule is referred to as reduction (a reduction in the oxidation state).
  • In a redox reaction, the oxidation and reduction processes always happen simultaneously.

IDENTIFYING REDOX REACTION:

Because two separate elements appear as free elements (oxidation number of 0) (zinc and copper in the example below) on one side of the equation and as components of a molecule on the other, single-replacement processes like the one given below, are redox reactions. As a result, the oxidation number of the substance must change.

               Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)

Oxidation half-reaction: Zn → Zn²⁺ + 2e–

Reduction half-reaction: Cu²⁺ + 2e– → Cu

Because elemental oxygen (O2) functions as the oxidizing agent and is reduced, combustion processes are redox reactions.

                   S(s) + O₂ (g) → SO₂ (g)

Because elements are generally changed into compounds, and vice versa, most combination and decomposition processes are redox reactions.

                       2H₂O → 2H₂ + O₂

Here, H+ is oxidized, and O- is reduced.

Redox-Reaction Source

NOW LET’S LOOK AT A FEW REACTIONS THAT ARE NOT REDOX:

Because ions are merely merged without any electron transfer, double-replacement events like those below aren't redox reactions.

           BaCl₂ (aq) + Na₂SO₄ (aq) → BaSO₄ (s)+ 2NaCl(aq)

If you calculate the oxidation numbers on all the ions, you will realize that the oxidation number of all the elements remains unchanged after the reaction.

Double-Replacement-Reaction

Source

Instead of an electron, a hydrogen ion is transferred in acid-base reactions. Acid base reactions, such as the one beneath, are not redox reactions.

                CH₃COOH + NH₃ ⇌ CH₃COO– + NH₄+

CONCLUSION

  • Redox reactions are oxidation-reduction chemical processes in which the oxidation states of the reactant changes.
  • Decomposition, combustion, Disproportionation, Displacement & Combination Reactions are the 5 major types of redox reactions.
  • Because ions are merely recombined without any electron transfer, double-replacement processes are not redox.

FAQs:

1. What is the definition of redox?

All chemical processes in which atoms' oxidation states are altered are redox (oxidation-reduction) reactions. The loss of electrons—or the rise in oxidation state—by a molecule, atom, or ion is called oxidation. During reduction, a molecule, atom, or ion gains electron—or decreases its oxidation state.

2. What is an example of redox reaction?

H₂ + F₂ → 2HF. Following that, the hydrogen and fluorine ions unite to produce hydrogen fluoride. F₂ is an oxidizing agent, whereas H₂ is a reducing agent in this reaction.

3. What types of reactions are redox reactions?

Decomposition Reaction, combustion reactions, Disproportionation Reaction, Displacement Reaction & Combination Reactions are the 5 major types of redox reactions.

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SOURCES:

  1. Identifying Redox Reactions. https://www.ck12.org/c/chemistry/identifying-redox-reactions/lesson/Identifying-Reaction-Types-CHEM/. Accessed 7 Feb 2022.
  2. Acid-Base Reactions. https://courses.lumenlearning.com/boundless-chemistry/chapter/acid-base-reactions/. Accessed 7 Feb 2022.