Posted by Sam on .
If the standard enthalpy of combustion of octane, C8H18(l) is -5471 kJ/mol, calculate the enthalpy change when 1.00 kg of octane are burned. the molar mass of octane is 114 g/mol
First we will find out the amount of grams of octane burned.
1 kg octane * 1000 g / 1 kg = 1000 g octane.
Now we will find the moles of octane burned:
1000 g octane / 114 g/mol octane = 8.772 mol octane burned.
Now that we have the amount of moles, we can find out how much enthalpy changed by multiplying the moles of octane burned times that amount of heat lost per mole.
-5471 kJ/mol * 8.772 mol = -48000 kJ