To balance the combustion reaction of butene (C4H8) with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O), we can follow these steps:
The unbalanced reaction is:
\[ \text{C}_4\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} \]
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Count the number of carbon, hydrogen, and oxygen atoms on the reactants' side:
- There are 4 carbon atoms in C4H8.
- There are 8 hydrogen atoms in C4H8.
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Balance the carbon atoms by putting a coefficient of 4 in front of CO2: \[ \text{C}_4\text{H}_8 + \text{O}_2 \rightarrow 4\text{CO}_2 + \text{H}_2\text{O} \]
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Balance the hydrogen atoms by putting a coefficient of 4 in front of H2O: \[ \text{C}_4\text{H}_8 + \text{O}_2 \rightarrow 4\text{CO}_2 + 4\text{H}_2\text{O} \]
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Count the oxygen atoms now on the products' side:
- From 4 CO2: \(4 \times 2 = 8\) oxygen atoms.
- From 4 H2O: \(4 \times 1 = 4\) oxygen atoms.
- Total oxygen on the product side = \(8 + 4 = 12\) oxygen atoms.
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Balance the oxygen atoms by determining how many O2 molecules are needed:
- Since each O2 has 2 oxygen atoms, for 12 oxygen atoms, we need \( \frac{12}{2} = 6\) O2 molecules.
The balanced equation is: \[ \text{C}_4\text{H}_8 + 6\text{O}_2 \rightarrow 4\text{CO}_2 + 4\text{H}_2\text{O} \]
So, the coefficients are:
- 1 for C4H8
- 6 for O2
- 4 for CO2
- 4 for H2O
Thus, the complete balanced combustion reaction is:
\[ 1\text{C}_4\text{H}_8 + 6\text{O}_2 \rightarrow 4\text{CO}_2 + 4\text{H}_2\text{O} \]