Question

The combustion of 0.0222g of isooctane vapor, C8H18(g), at constant pressure raises the temperature of a calorimeter 0.400 degrees C. The heat capacity of the calorimeter and water combined is 2.48kJ/degrees C. Find the molar heat of combustion of gaseous isooctane.

Answer 1

Answer:

ΔH = 5102.88 KJ/mol

Explanation:

• Qp = ΔH = CpΔT... constant pressure

∴ Cp = 2.48 KJ/°C

∴ ΔT = 0.400°C

∴ Mw C8H18(g) = 114.22 g/mol

∴ mol C8H18(g) = (0.0222 g)×(mol C8H18/114.22 g) = 1.944 E-4 mol C8H18

⇒ ΔH = (2.48 KJ/°C)×(0.400°C) = 0.992 KJ

⇒ ΔH = 0.992 KJ/ 1.944 E-4 mol C8H18

⇒ ΔH = 5102.88 KJ/mol