Question

Consider the following experiment performed by students in the Physical Chemistry class last semester: Benzoic acid, C6H602, was combusted in a bomb calorimeter, resulting in a 2.3°C increase in temperature of the calorimeter (part of the surroundings). 2 C.H.O2 (s) + 15 O2(g) 12 CO2(g) + 6H20 (1) A. Based on the reaction above and described observations, indicate the sign of the thermodynamic changes for the reaction and briefly support your selection. Thermodynamic Change Sign (+,-, or 0) Rationale ΔΗ B. Is the combustion of benzoic acid a spontaneous or nonspontaneous process? Briefly explain your answer.

benzoic acid was combusted in a bomb calorimeter resulting in a 2.3 degree C incresse

Answer 1

Hi there, i am truely sorry for not being able to answer part II as it requires Appendix C from your text book. Hence i am gonna answer Part I in full.

Part I

A) ΔH (enthalpy change) = - (negative sign), by definition exothermic reactions (heat releasing reactions) have a negative sign because products energy are lower than reactants energy (Final - initial = negative sign)

ΔS (entropy change) = + (positive sign), the difference between sum of product moles - sum of reactant moles is positive ( Δn = moles product (12+6)- moles reactant (2+15)) = 1. By definition solid to either liquid or gaseous transformation always accompanied by increase in entropy.

B) The combustion of reaction in forward direction is spontaneous because energy is released and dissipated to surroundings, according to the Gibbs free energy relationship ΔG = ΔH - TΔS, we get negative sign for ΔG. A negative sign of free energy indicates a spontaneous reaction.

Hope this helped you!

Thank You So Much!

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