When 0.438 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 26.0 ∘C to 29.4 ∘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.
Mass of biphenyl = 0.438 gm
biphenyl molar mass = 154.21 g/mol
Moles of Biphenyl = 0.438 g / 154.21 g/mol = 0.00284 Moles
heat capacity of the bomb calorimeter = 5.86 kJ/∘C
Temperatre raised in calorimeter = 29.4 ∘C - 26.0 ∘C = .3.4 ∘C
Heat relased by 0.438 g of biphenyl = .3.4 ∘C x 5.86 kJ/∘C = 19.924 Kilo Joules
Combustion of one mole of biphenyl = 19.924 Kilo Jolution / 0.00284 Moles = 7015.49 Kilo Joules / Mole
Hence ΔErxn for the combustion of biphenyl = 7015.49 Kilo Joules / Mole
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