Which reactions are oxidation-reduction reactions? Check all that apply. FeS(s) + 2HCl(aq) → H2S(g) + FeCl2(g)

AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3

2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(g)

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

2C₃H₆(g) + 9O₂(g) → 6CO₂(g) + 6H₂O(g)

Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)

Given

Reaction

Required

Oxidation-reduction reactions

Solution

In a redox reaction there will be a change in oxidation number

Oxidation: there is an increase in oxidation number

Reduction: there is a decrease in the oxidation number

1. 2C₃H₆(g) + 9O₂(g) → 6CO₂(g) + 6H₂O(g)

C in C₃H₆ = 3.C+6.+1=0⇒3C=-6⇒C=-2

C in CO₂ = C+2.(-2)=0⇒C=4

-2 to +4 ⇒ oxidation

O in O₂ = 0

O in H₂O = 2.+1+O=0⇒O=-2

0 to -2 ⇒reduction

2. Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)

Fe in Fe₂O₃(s) = +2

Fe in Fe(l) = 0

+2 to 0 ⇒ reduction

C in CO = +2

C in CO₂ = +4

+2 to +4 ⇒ oxidation