You have a gaseous octane (C8H18(g)). Calculate the lower heating value (LHV) and higher heating value (HHV) of the given fuel in MJ/kg(fuel).

To calculate the lower heating value (LHV) and higher heating value (HHV) of a fuel, we need the composition of the fuel in terms of its elemental components and their respective enthalpy values.

Here's how you can calculate the LHV and HHV of octane (C8H18):

1. Determine the elemental composition of octane:
Octane (C8H18) is composed of carbon (C) and hydrogen (H). The molecular formula indicates that there are 8 carbon atoms and 18 hydrogen atoms in each octane molecule.

2. Find the enthalpy of combustion for each component:
The enthalpy of combustion is the heat released when one mole of the substance undergoes complete combustion. The enthalpy of combustion values for carbon (C) and hydrogen (H) are as follows:
- Enthalpy of combustion of carbon (C): -393.5 kJ/mol
- Enthalpy of combustion of hydrogen (H): -285.8 kJ/mol

3. Calculate the molar mass of octane (C8H18):
The molar mass of each element can be found on the periodic table. We can calculate the molar mass of octane by adding up the molar masses of all the atoms in the molecule:
Molar mass of C8H18 = (8 * 12.01 g/mol) + (18 * 1.01 g/mol)

4. Calculate the LHV:
The LHV is the heat released during complete combustion without accounting for the heat absorbed by the water formed. To calculate the LHV, we multiply the number of moles of carbon and hydrogen in octane by their respective enthalpy of combustion, and sum up the values:
LHV = (8 * -393.5 kJ/mol) + (18 * -285.8 kJ/mol), and then convert the value to MJ/kg by dividing by the molar mass of octane and multiplying by 1000.

5. Calculate the HHV:
The HHV takes into account the heat absorbed by any water vapor formed during combustion. To calculate the HHV, we need to consider the heat released during the combustion of the carbon and hydrogen atoms, as well as the heat released when water vapor is condensed back into liquid water. The enthalpy of condensation of water vapor is -44 kJ/mol. So the calculation for the HHV is as follows:
HHV = (8 * -393.5 kJ/mol) + (18 * -285.8 kJ/mol) - (10 * 44 kJ/mol), and then convert the value to MJ/kg by dividing by the molar mass of octane and multiplying by 1000.

By following these steps, you can calculate the lower heating value (LHV) and higher heating value (HHV) of octane in MJ/kg.