how to balance redox reaction in acidic med. HSO 4 - +As 4 +Pb 3 O 4 ​ = PbSO 4 +H 2 AsO 4 -

							
1)First write down the half reactions:-
 a) Oxidation Half Reaction – As40 is getting oxidised to As+5 .
 Now balance the reaction by first balancing the main atom and then by adding electrons
 
As40 ------- 4As+5 + 20e- ….….….…..(1)
 
b)Reduction half reaction – Here (Pb3)+8 is getting reduced to Pb+2
 Now balance the reaction by first balancing the main atom and then by adding electrons
 
2e-+(Pb3)+8 ---------- 3Pb+2….….…..(2)
 
2)Now as the electrons added are not equal in both the halfs make it equal by multiplying (2) by 10..
 
As40-------4As+5+20e-
20e-+10(Pb3)+8 -------30Pb+2
 
3)Now add both the reactions to obtain the stoichiometric coefficients...
As40+10(Pb3)+8----------4As+5+30Pb+2
 
4)Then write them in their reaction form.
HSO4- +As4 +10Pb3O4​ ------- 30PbSO4+4H2AsO4-
5)Now balance the other main atoms , here S is unbalanced.
30HSO4+As4 +10Pb3O4​ ------ 30PbSO4+4H2AsO4
6)Now balance the no of oxygens by adding H2O
30HSO4+As4 +10Pb3O4​ ------ 30PbSO4+4H2AsO4+24H2O
7)Finally balance the no of hydrogen atoms by adding H+ ions to the other side.
30HSO4+As4 +10Pb3O4+26H+​ ------ 30PbSO4+4H2AsO4+24H2O
THE BALANCED REACTION:-
30HSO4+As4 +10Pb3O4+26H+​ ------ 30PbSO4+4H2AsO4+24H2O
						

							
 
1)First write down the half reactions:-
 a) Oxidation Half Reaction – As40 is getting oxidised to As+5 .
 Now balance the reaction by first balancing the main atom and then by adding electrons
 
As40 ------- 4As+5 + 20e- ….….….…..(1)
 
b)Reduction half reaction – Here (Pb3)+8 is getting reduced to Pb+2
 Now balance the reaction by first balancing the main atom and then by adding electrons
 
2e-+(Pb3)+8 ---------- 3Pb+2….….…..(2)
 
2)Now as the electrons added are not equal in both the halfs make it equal by multiplying (2) by 10..
 
As40-------4As+5+20e-
20e-+10(Pb3)+8 -------30Pb+2
 
3)Now add both the reactions to obtain the stoichiometric coefficients...
As40+10(Pb3)+8----------4As+5+30Pb+2
 
4)Then write them in their reaction form.
HSO4- +As4 +10Pb3O4​ ------- 30PbSO4+4H2AsO4-
 
5)Now balance the other main atoms , here S is unbalanced.
30HSO4+As4 +10Pb3O4​ ------ 30PbSO4+4H2AsO4
 
6)Now balance the no of oxygens by adding H2O
30HSO4+As4 +10Pb3O4​ ------ 30PbSO4+4H2AsO4+24H2O
 
7)Finally balance the no of hydrogen atoms by adding H+ ions to the other side.
30HSO4+As4 +10Pb3O4+26H+​ ------ 30PbSO4+4H2AsO4+24H2O
 
THE BALANCED REACTION:-
30HSO4+As4 +10Pb3O4+26H+​ ------ 30PbSO4+4H2AsO4+24H2O