Question

white phosphorus reacts with caustic soda,the products are PH3 and NaH2PO2.This reaction is an example of : (A) Oxidation (B) Reduction (C) Disproportionation (D) Neutralisation

Answer 1

P4+3NaOH+3H2O+3H2O→PH3+3NaH2PO2,oxidation state of P in the LHS side=0
In right side
PH3
x+3(+1)=0
x=-3
NaH2PO2
1+2(1)+x+2(-2)=0
thus from 0 oxidation state there is both reduction in the oxidation no and increase in oxidation no occur.
The first reaction is reduction and the second reaction is oxidation.Such type of redox reaction from the same molecule.ie one undergoes oxidation & the other undergoes reduction is called disproportion reaction.

Answer 2

Answer:

Explanation:

P4+3NaOH+3H2O+3H2O→PH3+3NaH2PO2,oxidation state of P in the LHS side=0

In right side

PH3

x+3(+1)=0

x=-3

NaH2PO2

1+2(1)+x+2(-2)=0

thus from 0 oxidation state there is both reduction in the oxidation no and increase in oxidation no occur.

The first reaction is reduction and the second reaction is oxidation.Such type of redox reaction from the same molecule.ie one undergoes oxidation & the other undergoes reduction is called disproportion reaction.