Answer:
The enthalpy of combustion of ethanol is -1430 kJ/mol, which means that for every mole of ethanol that is burned, 1430 kJ of heat is released.
To determine the amount of heat given off from the combustion of 1 dm³ of ethanol, we need to first calculate the number of moles of ethanol in 1 dm³.
1 dm³ is equivalent to 1000 cm³. Since the density of ethanol is 0.79 g/cm³, the mass of 1 dm³ of ethanol can be calculated as:
mass = density x volume
mass = 0.79 g/cm³ x 1000 cm³
mass = 790 g
To convert this mass to moles, we need to divide by the molar mass of ethanol:
moles = mass / molar mass
moles = 790 g / 46 g/mol
moles = 17.17 mol
Therefore, 1 dm³ of ethanol contains 17.17 moles of ethanol.
To calculate the heat given off from the combustion of 1 dm³ of ethanol, we can use the following equation:
heat = enthalpy of combustion x moles of ethanol
heat = -1430 kJ/mol x 17.17 mol
heat = -24,551 kJ
Therefore, the heat given off from the combustion of 1 dm³ of ethanol is -24,551 kJ, or approximately 24,551 kJ of heat is released.