Question

Given the balanced equation representing a reaction:

2KClO3(s) ==> 2KCl(s) + 3O2(g)
The oxidation state of chlorine in this reaction changes from
(1) -1 to +1 (3) +1 to -1
(2) -1 to +5 (4) +5 to -1

Answer 1

Oxidation # of Cl in Potassium Chlorate:
Let x= oxidation state of Cl

`KClO_(3)`
(+1) + (x) + (-2 * 3) = 0
(x) - 5 = 0
∴ x = +5

Oxidation State of Cl in Potassium Chloride
Let oxidation state of Cl = y
KCl
(+1) + (x) = 0
x = 0

Thus Cl goes from +5 to -1 (option 4) [REDUCTION]

Note: oxidation of :
O is alway -2 unless told otherwise by instructions
K is +1