Final answer:
To calculate the heats of combustion for alcohols like methanol, ethanol, and propanol, one must write balanced chemical equations for their combustion, use standard enthalpies of formation, and apply stoichiometry to compute the heat released per mole of the alcohol.
Step-by-step explanation:
Calculating Heats of Combustion for Alcohols
The subject matter deals with the combustion of alcohols, such as methanol, ethanol, and propanol, and the calculation of their respective heats of combustion. To determine the heat of combustion of methanol (CH3OH), we must consider the balanced chemical reaction for its combustion. Typically, the combustion process for alcohols involves the fuel reacting with oxygen from the air to produce carbon dioxide (CO2) and water (H2O), releasing heat in the process.
Steps for Calculating the Heat of Combustion:
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- Write a balanced chemical equation for the complete combustion of the alcohol.
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- Use enthalpies of formation for the reactants and products to determine the enthalpy change (∆H).
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- Apply the stoichiometry of the reaction to calculate the heat released per mole of fuel.
The heat of combustion is given by the difference in enthalpy of the reactants and products. It's important to ensure that states of matter are correctly indicated, as they can affect the enthalpy values used in calculations.
For the problem involving ethanol (C2H5OH), the heat of combustion is determined by using the provided enthalpies of formation and the balanced equation for the combustion:
C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(l)
Using the enthalpies of formation, we calculate the heat of combustion. The overall heat of combustion for ethanol would be calculated by subtracting the total enthalpies of formation of the reactants from the products, multiplied by their respective stoichiometric coefficients.