Answer:
Balanced reaction: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)
Reduced: O₂
Oxidized : C₃H₈
Explanation:
For the given reaction:
C₃H₈(g) + O₂(g) → CO₂(g) + H₂O(l)
In the reactants, there are 3 C, and in the products only one, so we multiply CO₂ by 3:
C₃H₈(g) + O₂(g) → 3CO₂(g) + H₂O(l)
In the reactants, there are 8 H, and in the products, there are 2 H, so we multiply H₂O by 4:
C₃H₈(g) + O₂(g) → 3CO₂(g) + 4H₂O(l)
In the reactants are 2 O, and in the products 10 O, so we multiply O₂ by 5:
C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)
The reaction is balanced.
Let's identify the oxidation number (Nox) of the elements in each compound.
C₃H₈:
H has fix Nox equal to +1, and the molecule is neutral, so, calling x the Nox of C:
3x + 8 = 0
3x = -8
x = -8/3
O₂:
Because is a pure compound, the Nox of O is 0.
CO₂:
The Nox of O is fix equal to -2, and the molecule is neutral, so, calling x the Nox of C:
2x -4 = 0
2x = 4
x = +2
H₂O:
The Nox of H and O are fixed, respectively, +1 and -2.
So, the carbon in C₃H₈ is oxidized because its Nox is increasing, and oxygen in O₂ is reduced because its Nox is decreasing.
