How Many Moles of Oxygen Are Required to Burn One Mole of Ethane Completely?

When considering the complete combustion of ethane (C2H6), determining the amount of oxygen needed is a crucial aspect of understanding chemical reactions. The combustion of ethane is an exothermic process, where the reactants are transformed into products, primarily carbon dioxide and water. The balanced chemical equation for this reaction is vital to calculating the required amount of oxygen.

The Balanced Chemical Equation and Stoichiometry

These steps outline the necessary procedure:

Write the unbalanced equation for the combustion of ethane: C2H6 O2 → CO2 H2O

To balance this equation, we need to ensure the number of atoms on each side of the equation is equal. This process involves adjusting the coefficients:

Step 1: Balance the carbon atoms: We have 2 carbon atoms on the left, so we need 2 carbon dioxide molecules on the right:

C2H6 O2 → 2 CO2 H2O

Step 2: Balance the hydrogen atoms: We have 6 hydrogen atoms on the left, so we need 3 water molecules on the right:

C2H6 O2 → 2 CO2 3 H2O

Step 3: Balance the oxygen atoms: We have 7 oxygen atoms on the left (3 from oxygen in C2H6 and 4 from O2), so we need 7/2 oxygen molecules. To keep the equation simple, we multiply all coefficients by 2:

2 C2H6 7 O2 → 4 CO2 6 H2O

From the balanced equation, we can see that 2 moles of ethane require 7 moles of oxygen. Therefore, for 1 mole of ethane, the amount of oxygen required is:

3.5 moles O2 frac{7 text{ moles O}2}{2 text{ moles C}2H6}

Properties of the Reaction

1. Enthalpy (ΔH): The change in enthalpy, denoted as ΔH, for the reaction is calculated as -1448.8 kJ. This indicates that the reaction is exothermic, meaning it releases heat.

2. Free Energy (ΔG): The change in free energy, denoted as ΔG, at 2200°C is calculated as -1456.4 kJ. A negative value for ΔG suggests that the reaction is thermodynamically favorable.

Conclusion

Understanding the stoichiometry and the properties of the reaction is essential for predicting and controlling the combustion of ethane. The required amount of oxygen for complete combustion and the characteristics of the reaction highlight the exothermic nature and thermodynamic stability of this process.

Key Takeaways:

2 moles of ethane require 7 moles of oxygen for complete combustion. The reaction is exothermic with a ΔH of -1448.8 kJ. The process is thermodynamically favorable with a ΔG of -1456.4 kJ at 2200°C.

These points emphasize the importance of proper precautions and understanding in handling and reacting ethane.