Question

Balance
C3H8+ O2 -CO2+H2O

Answer 1

To balance the chemical equation for the combustion of propane (C₃H₈), we start with the unbalanced equation:

\[ \text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} \]

### Steps to Balance:

1. **Count the number of atoms of each element** in the reactants and products:
- Reactants:
- C: 3 (from C₃H₈)
- H: 8 (from C₃H₈)
- O: 2 (from O₂)

- Products:
- C: 1 (from CO₂)
- H: 2 (from H₂O)
- O: 3 total (2 from CO₂ + 1 from H₂O)

2. **Balance the carbon (C) atoms**:
We have 3 carbon atoms in C₃H₈, so we need 3 CO₂ molecules.
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow 3 \text{CO}_2 + \text{H}_2\text{O}
\]

3. **Balance the hydrogen (H) atoms**:
We have 8 hydrogen atoms in C₃H₈, so we need 4 H₂O molecules (since each H₂O contributes 2 H atoms).
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow 3 \text{CO}_2 + 4 \text{H}_2\text{O}
\]

4. **Now count the oxygen (O) atoms**:
- On the right side, we have 3 CO₂ (6 O) + 4 H₂O (4 O) = \(6 + 4 = 10\) O atoms.
- On the left side, O₂ contributes oxygen. If we use x O₂, we have \(2x\) oxygen atoms.

Set up the equation:
\[
2x = 10
\]
Solving for x gives:
\[
x = 5
\]

So, we need 5 O₂ molecules.

5. **Write the balanced equation**:
Putting it all together, we have:
\[
\text{C}_3\text{H}_8 + 5 \text{O}_2 \rightarrow 3 \text{CO}_2 + 4 \text{H}_2\text{O}
\]

### Final Balanced Equation:
\[
\text{C}_3\text{H}_8 + 5 \text{O}_2 \rightarrow 3 \text{CO}_2 + 4 \text{H}_2\text{O}
\]