Answer:
2C₃H₆ + 9O₂ ⟶ 6CO₂ + 6H₂O
Explanation:
The repeating unit in PP is C₃H₆.
The unbalanced equation for the combustion of one repeating unit is
C₃H₆ + O₂ ⟶ CO₂ + H₂O
Here's how to balance the equation.
1. Pick the most complicated-looking formula (C₃H₆).
Put a 1 in front of it.
1C₃H₆ + O₂ ⟶ CO₂ + H₂O
2. Balance C.
We have fixed 3C on the left. We need 3C on the right.
Put a 3 in front of CO₂.
1C₃H₆ + O₂ ⟶ 3CO₂ + H₂O
3. Balance H.
We have fixed 6H on the left. We need 6H on the right.
Put a 3 in front of H₂O.
1C₃H₆ + O₂ ⟶ 3CO₂ + 3H₂O
4. Balance O
We have fixed 9O on the right. we need 9O on the left.
Uh, oh. Fractions. we need 4½ O₂.
Multiply every coefficient by two.
2C₃H₆ + O₂ ⟶ 6CO₂ + 6H₂O
Now, we have 18O on the right. Balance O by putting a 9 in front of O₂.
2C₃H₆ + 9O₂ ⟶ 6CO₂ + 6H₂O
All species have a coefficient. The equation should now be balanced.
5. Check that all atoms are balanced
The balanced equation should have the same number of atoms on each side of the reaction arrow.
[tex]\begin{array}{ccc}\textbf{Atom} & \textbf{On the left} & \textbf{On the right}\\\text{C} & 6 & 6\\\text{H} & 12 & 12\\\text{O} & 18 & 18\\\end{array}[/tex]
The balanced equation is
2C₃H₆ + 9O₂ ⟶ 6CO₂ + 6H₂O
