What mass of octane (in g) is required to produce 8210 kJ of heat?

184.8 g

Explanation:

Step 1: Write the balanced thermochemical equation

C₈H₁₈(l) + 25/2 O₂(g) ⇒ 8 CO₂(g) + 9 H₂O(g)   ΔH°rxn = -5074.1 kJ

Step 2: Calculate the moles of octane required to produce 8210 kJ of heat

According to the thermochemical equation, 5074.1 kJ of heat are released per mole of octane consumed.

-8210 kJ × 1 mol C₈H₁₈/(-5074.1 kJ) = 1.618 mol

Step 3: Calculate the mass corresponding to 1.618 moles of octane

The molar mass of C₈H₁₈ is 114.23 g/mol.

1.618 mol × 114.23 g/mol = 184.8 g