Question

General Chemistry II Part II. Fuel efficiency (6 pts) Fuel efficiency is the efficiency of the conversion of chemical energy contained in a fuel into work. Let's see which one of these fuels (hydrogen gas or liquid propane) will allow us to do more electrical work. Use the thermodynamic data provided to answer the following questions: 1. First determine the amount of heat released in direct combustion of (a) 1 mole of hydrogen gas; (b) 1 mole of liquid propane (a) Hz(g): (b) C3H8(1): 2. The amount of useful work other than the expansion work that a reaction can produce is given by the AG rx of the process. So the value for the maximum electrical work that can be done in a reaction can be obtained from AG . And if both AH and AS are known it can be calculated using AᏳ°rxn = ᎪH° en - TᎪᏛ°ran« What is the maximum amount of electrical work (per mole of fuel) that the same reactions can perform when carried out at 298K? (a) H2(g): (6) C3H8(1): Which of the two fuels allows us to do more electrical work per 1 mole of it used? Per mol_ is_ times more efficient than

Answer 1

o th and O₂ is in elemental state, (DHA) 2 } zo The = (DHf) 10 = -285.8 KJ / md. AHC = - 285.8 kJ/mol Enthalpy of combustion for 1 mol of the Che (e) +5069) -->3.603 Theod DH c = 3(144) coz + 4 QHS) Ho - So fliste +Scotyl oz) = 3(-393.5)+4(-285.6) -(403.a) Kilmol Kilmal Kilmol. 1 AHE= - 22 19.8 kJ/mol Thus, amoent of heat release by combustion of 1 mol of propare is - 2299.8 kJ