Have out compound unit worksheet and 245 if not checked.

Objective: Determine the heat of combustion for equations, grams, and moles of a substance.

If the reaction 2 moles of C8H18 produces 10,900 KJ, how many grams of octane would be required to produce 700,000 kJ?

Catalyst: 2C8H18 + 25 O2 → 16 CO2 + 18 H2O

H = −10,900 kJΔ

Heat of Combustion

• How much energy is given off per amount of substance burned.– Heat of combustion: kJ/g (kilojoules per gram)– Molar heat of combustion: kJ/mol (kilojoules per mole)

A substance burns and gives off 1,000 kJ of heat. If 20 g of the substance burned, what is the heat of combustion?

3,500 kJ of heat were given off after 72 g of a substance burned. What is the heat of combustion?

3.5 moles of a substance is burned and 7,000 kJ is released. What is the molar heat of combustion?

2C8H18 + 25 O2 → 16 CO2 + 18 H2O H = −10,900 kJΔ

What is the molar heat of combustion of octane?

10,900 kJ per 2 moles =

What is the heat of combustion of octane?

2C8H18 + 25 O2 → 16 CO2 + 18 H2O H = −10,900 kJΔ

• How many grams of octane would be required to produce 150,000 kJ?

• If 1.5 moles of octane were burned, how many kJ of energy would be released?

kJ