Part D: Use Hess Liquid butane (C4H10), the fuel used in many disposable lighter

Question

Part D: Use Hess

Liquid butane (C4H10), the fuel used in many disposable lighters, has Delta H = -147.5 kJ/mol and a density of 0.579 g/mL (Use necessary data from Table 8.2 and Appendix B in the textbook) Write a balanced equation for the combustion of butane. Express your answer as a chemical equation. Identify all of the phases in your answer. Use Hess's law to calculate the enthalpy of combustion in kJ/mol. Express your answer using one decimal place. Use Hess's law to calculate the enthalpy of combustion in kJ/g. Express your answer using four significant figures.

Explanation / Answer

(B) C4H10(l) + 13/2 O2(g) => 4 CO2(g) + 5 H2O(g)

DHc in kJ/mol = DHf(products) - DHf(reactants)

= 4 x DHf(CO2) + 5 x DHf(H2O) - DH(C4H10) - 13/2 x DHf(O2)

= 4 x (-393.5) + 5 x (-241.8) - (-147.5) - 13/2 x 0

= -2635.5 kJ/mol

(C) DHc in kJ/g = (DHc in kJ/mol)/molar mass of C4H10 in g/mol

= -2635.5/58.12

= -45.35 kJ/g

(D) DHc in kJ/mL = (DHc in kJ/g) x density of C4H10 in g/mL

= -45.35 x 0.579

= -26.26 kJ/mL

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