Question

Hi, can anyone please help me with this? i have no clue how to define if a reaction is Oxidation reduction or not. Thanks a lot

OXIDATION-REDUCTION Introduction Chemists refer to reactions which involve a transfer of electrons from one reactant to another as oxidation reduction reactions of just "redox" reactions. Oxidation is defined as a loss of electron and reduction as a gain of electron by a substance during a chemical reaction. The loss of electrons by one substance must always be accompanied by a gain of electrons by another substance and thus oxidation and reduction must always take place simultaneously. The total number of electrons lost in a redox reaction by one reactant is always equal to the total number of electrons gained by another substance and is the principle used in balancing oxidation reduction equations by both the oxidation number and the half-reaction equation method. The substance that gains electron and is thus reduced is called an oxidizing agent, since it helps in oxidizing agent, since it helps in oxidizing another substance. Similarly, the substance that loses electrons and is oxidized in a reaction is called a reducing agent. For example in the reaction: Znce+ Cu?(aq) → Zn (aq) + Cu(aq) which occurs in a voltaic cell called the Daniel Cell, solid zinc loses two electrons per atom of zinc (it increases its oxidation number from zero to +2) and is oxidized. It is, therefore, said to be a reducing agent. Each cupric ion gains two electrons (it decreases its oxidation number from +2 to zero) and is reduced. Since it helps oxidize the zinc by accepting electrons it is an oxidizing agent. Procedure Part I To 1 mL of 0.10 M ferric nitrate, Fe(NO3), solution add a few drops of 6M ammonia, NH4OH. a) Observation Dark orange pt precipito te b) Write an equation illustrating the reaction (note: ferric hydroxide, Fe(OH)3, is a very insoluble hydroxide, Ksp = 6x10). Fe(NO) + 3 (NHGOH) FEO (04) + 3NHO NO THEO

Answer 1

Oxidation - Reduction

old concept

Oxidation : gaining of oxygen atom or any electronegative element

Reduction: Removal of Hydrogen atom or any electropositive element.

For example:

H2 + I2 -------------------> 2HI

H2 undergoes oxidation because I (electronegative element) attache to H.

I2 undergoes Reduction because H (electropositive element) attache to I.

Modern Concept

( electronic concept)

Oxidation : Removal of electron

Reduction: Gain of electron

For example

Zn -------------> Zn2+ 2e (Oxidation)

Cu2+ + 2e -----------> Cu (Reduction)

(Oxidation Number method)

KMnO4 + C2O4H2.2H2O + H2SO4 -------------------> K2SO4  + MnSO4 + CO2 + H2O

Oxidation : increase in oxidation number

Reduction : Decrease in oxidation number

Oxidation : C2O4H2.2H2O

Reason : Oxidation number of Carbon increase from +3 to +4 in CO2

eduction : KMnO4

Reason : Oxidation number of Mn Decrease from +7 to +2.

Oxidising Agent

the substance which oxidised to other and itself undergoes reduction

Reducing Agent

the substance which Reduced to other and itself undergoes oxidation