BackCombustion of Ethanol: Equation Balancing and Stoichiometric Calculations
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Combustion Reactions and Stoichiometry
Combustion of Ethanol
The combustion of ethanol (C2H5OH) is a chemical reaction in which ethanol reacts with oxygen to produce carbon dioxide and water. This is an example of a complete combustion reaction, which is important in both energy production and biochemical processes.
Combustion Reaction: A reaction where a substance reacts with oxygen gas, releasing energy, carbon dioxide, and water.
Ethanol: A simple alcohol with the formula C2H5OH.
Balanced Chemical Equation
To write and balance the combustion equation for ethanol:
General form: Alcohol + O2 → CO2 + H2O
The unbalanced equation:
C2H5OH + O2 → CO2 + H2O
Balancing the equation:
Count atoms of each element on both sides.
Balance C, then H, then O.
Balanced equation:
Stoichiometric Calculation: Mass of CO2 Produced
To find the mass of CO2 produced when 10.0 g of ethanol burns completely:
Calculate moles of ethanol:
Molar mass of C2H5OH = (2 × 12.01) + (6 × 1.01) + 16.00 = 46.08 g/mol
Moles of ethanol =
Use the balanced equation to find moles of CO2:
From the equation: 1 mol ethanol produces 2 mol CO2
Moles of CO2 =
Calculate mass of CO2 produced:
Molar mass of CO2 = 12.01 + (2 × 16.00) = 44.01 g/mol
Mass of CO2 =
Summary Table: Stoichiometric Relationships
Substance | Moles Used/Produced | Molar Mass (g/mol) | Mass (g) |
|---|---|---|---|
Ethanol (C2H5OH) | 0.217 | 46.08 | 10.0 |
CO2 | 0.434 | 44.01 | 19.1 |
Key Points
Combustion reactions are a major source of energy and are important in metabolism and industry.
Balancing chemical equations ensures the law of conservation of mass is obeyed.
Stoichiometry allows calculation of product amounts from given reactant quantities.
