More questions on Enthalpy Change and Standard Enthalpies of Formation

1) A city of 100,000 people uses approximately 1.0 ×〖10〗^11  kJ of energy per day. Suppose all of that energy comes from the combustion of liquid octane (C_8 H_18) to form gaseous water and gaseous carbon dioxide.

Use standard enthalpies of formation to calculate ΔH°_rxn  for the combustion of octane and then determine how many kilograms of octane are needed to provide this amount of energy.

2) Dry chemical hand warmers utilize the oxidation of iron to form iron oxide according to the following reaction:

4 Fe_((s))+3 O_(2 (g))→2 Fe_2 O_(3 (s))

Calculate ΔH°_rxn  for this reaction and calculate how much heat a hand warmer containing 15.0 g of iron powder produces.