Ethanol is a fuel that can be made from corn. How many kJ of heat energy are released when 3.00 kg of ethanol are burned?
C2H5OH(l) + 3O2(g) �¨ 2CO2(g) + 3H2O(g) H = -1406.8 kJ/mol
so how many moles is 3kg of C2H5OH?
given that, heat = -1406.8* moles ethanol
1406.8 kJ/mol x mols ethanol = ??
To find the amount of heat energy released when 3.00 kg of ethanol is burned, we need to use the given enthalpy change (∆H) value for the combustion of ethanol.
First, we convert the mass of ethanol from kilograms to moles. To do this, we need to know the molar mass of ethanol (C2H5OH), which can be calculated by adding up the atomic masses of the elements in the compound.
C: 12.01 g/mol
H: 1.01 g/mol (there are 6 hydrogens, so total mass is 1.01 * 6 = 6.06 g/mol)
O: 16.00 g/mol (there is 1 oxygen, so total mass is 16.00 * 1 = 16.00 g/mol)
Molar mass of ethanol (C2H5OH): 12.01 + 6.06 + 16.00 = 34.07 g/mol
Now, we can calculate the number of moles of ethanol in 3.00 kg:
Mass of ethanol = 3.00 kg = 3000 g
Moles of ethanol = Mass / Molar mass = 3000 g / 34.07 g/mol
Next, we use the balanced chemical equation to find the molar ratio between ethanol and heat energy:
C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g) ΔH = -1406.8 kJ/mol
From the equation, we see that the combustion of 1 mole of ethanol releases -1406.8 kJ of heat.
Finally, we can calculate the amount of heat energy released when 3.00 kg of ethanol is burned:
Heat energy released = Moles of ethanol * ΔH
Heat energy released = (3000 g / 34.07 g/mol) * (-1406.8 kJ/mol)
Simplifying this expression will give us the final answer in kilojoules (kJ).