# Problem: A city of 100,000 people uses approximately 1.0 x 1011 kJ of energy per day (an exothermic process). Suppose all of that energy comes from the combustion of liquid octane (C8H18). Use the given standard enthalpies of formation to find the ∆H for the combustion of octane and then determine how many kg of octane would be necessary to provide that amount of energy.                   C8H18   +   25/2 O2   →   8 CO2   +   9 H2O∆H for octane = -250.1 kJ/mol∆H for carbon dioxide = -393.5 kJ/mol∆H for water = -241.8 kJ/mol

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###### Problem Details

A city of 100,000 people uses approximately 1.0 x 1011 kJ of energy per day (an exothermic process). Suppose all of that energy comes from the combustion of liquid octane (C8H18). Use the given standard enthalpies of formation to find the ∆H for the combustion of octane and then determine how many kg of octane would be necessary to provide that amount of energy.

C8H18   +   25/2 O2   →   8 CO2   +   9 H2O

∆H for octane = -250.1 kJ/mol

∆H for carbon dioxide = -393.5 kJ/mol

∆H for water = -241.8 kJ/mol

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Enthalpy of Formation concept. You can view video lessons to learn Enthalpy of Formation. Or if you need more Enthalpy of Formation practice, you can also practice Enthalpy of Formation practice problems.

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What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Jahangeri's class at NVCC.