Question

When 0.601 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 26.1 ∘C to 30.3 ∘C.

Find ΔErxn for the combustion of biphenyl in kJ/mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/∘C.

Answer 1

Given

Mass of biphenyl = 0.601 g

Heat capacity of the bomb calorimeter = 5.86 k J / ⁰ C

Change in temperature = 30.3 ⁰ C - 26.1 ⁰ C = 4.2 ⁰ C

Molar mass of biphenyl ( C12H10 ) = ( 12 12.01 ) + ( 10 1.0079 ) = 154.20 g / mol

We have relation, E = Heat capacity of the calorimeter Change in temperature ( Molar mass / Mass )

E = 5.86 k J / ⁰ C 4.2 ⁰ C ( 154.20 g / mol / 0.601 g )

E = 5.86 k J / ⁰ C 4.2 ⁰ C 256.57 mol ^-1

E = 6314.7 k J / mol

ANSWER : E = - 6.31 10 ³ k J / mol