Question

Ethane and oxygen gas react to produce carbon dioxide and water.
C ₂H ₈ + O ₂ →
Complete the following:
What type of reaction is this? What would be the evidence that you would cite for this reaction?
Predict the products and balance the reaction.

Answer 1

The reaction between ethane (C₂H₆) and oxygen gas (O₂) to produce carbon dioxide (CO₂) and water (H₂O) is a **combustion reaction**. This type of reaction typically involves a hydrocarbon reacting with oxygen to produce carbon dioxide and water, usually releasing energy in the form of heat and light.

### Evidence for the Reaction
The main piece of evidence for the occurrence of a combustion reaction includes:
- The production of gases (CO₂ and H₂O vapor).
- Heat and light are produced, which can be observed as flames.
- The reaction consumes oxygen, which can be measured by a decrease in oxygen gas in the reaction environment.

### Predicting and Balancing the Reaction
1. Write the unbalanced chemical equation for the combustion of ethane:
\[
\text{C}_2\text{H}_6 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}
\]

2. Count the number of atoms of each element in the reactants and products:
- Reactants: 2 Carbon (C) in C₂H₆, 6 Hydrogen (H) in C₂H₆, O in O₂
- Products: Each CO₂ has 1 Carbon and each H₂O has 2 Hydrogens.

3. Balance the equation:
- Balance the carbon atoms:
\[
\text{C}_2\text{H}_6 + \text{O}_2 \rightarrow 2\text{CO}_2 + \text{H}_2\text{O}
\]

- Balance the hydrogen atoms (6 H in C₂H₆ will yield 3 H₂O):
\[
\text{C}_2\text{H}_6 + \text{O}_2 \rightarrow 2\text{CO}_2 + 3\text{H}_2\text{O}
\]

- Now balance the oxygen atoms. We have:
- On the product side: \(2 \times 2 = 4\) O from CO₂ and \(3 \times 1 = 3\) O from H₂O, totaling 7 O atoms.
- Therefore, we need \(\frac{7}{2}\) or \(3.5\) O₂ (since O₂ has 2 O atoms).
\[
\text{C}_2\text{H}_6 + \frac{7}{2} \text{O}_2 \rightarrow 2\text{CO}_2 + 3\text{H}_2\text{O}
\]

4. To eliminate the fraction, multiply the entire equation by 2:
\[
2\text{C}_2\text{H}_6 + 7\text{O}_2 \rightarrow 4\text{CO}_2 + 6\text{H}_2\text{O}
\]

### Final Balanced Equation:
\[
2\text{C}_2\text{H}_6 + 7\text{O}_2 \rightarrow 4\text{CO}_2 + 6\text{H}_2\text{O}
\]

This balanced equation indicates that two moles of ethane react with seven moles of oxygen to produce four moles of carbon dioxide and six moles of water.