Page 1 - Microsoft Word - Lesson note-1(Redox reaction)

SUBJECT – CHEMISTRY

CHAPTER – REDOX REACTIONS

SUBTOPIC – Types of reactions

KEYNOTES:

 Oxidation: It is defined as
(i)Addition of oxygen. Removal of hydrogen.
(ii)Addition of electronegative element. Removal of electropositive

element.
(iii)Increase in positive charge. Decrease in negative charge.
(iv)Loss of electron.
Example – Mg + O2 → 2MgO
H2S + Cl2 → 2HCl + S

SnCl2 + Cl2 → SnCl4
-
Na → Na + e
+
 Reduction: It is defined as
(i)Addition of hydrogen. Removal of oxygen.
(ii)Addition of electropositive element. Removal of electronegative
element.

(iii)Increase in negative charge. Decrease in positive charge.
(iv)Gain of electron.
Example – CuO + C → Cu + CO
Cl2 + H2 → 2HCl
2FeCl3 + H2 → 2FeCl2 + 2HCl

-
-
Cl + e → Cl
 Redox Reaction: It is the reaction in which both oxidation and reduction
takes place.
Example – Zn + CuSO4 → ZnSO4 +Cu
 Disproportionation reaction: It is the reaction in which same element
undergoes oxidation and reduction.

Example – 2H2O2 → 2H2O + O2
+
2+
2Cu (aq)→ Cu (aq)+ Cu(s)
 Oxidising agent or Oxidant: It is the substance which oxidises others but
itself get reduced.
Example – KMnO4, K2Cr2O7, CrO3, HNO3, H2SO4, MnO2, H2O2, O3, O2, F2 Cl2

KI + H2O2 → 2KOH + I2