About 86% of the world's electrical energy is produced by using steam turbines, a form of heat engine. In his analysis of an ideal heat engine, Sadi Carnot concluded that the maximum possible efficiency is defined by the total work that could be done by the engine, divided by the quantity of heat available to do the work (for example from hot steam produced by combustion of a fuel such as coal or methane). efficiency=w/q∗100 The fuel in high-efficiency natural gas vehicles consists primarily of methane CH4 ΔHf (kJ/mol) ΔGf (kJ/mol) S (J/mol-K) CH4(g) -74.6 -50.5 186.3 O2(g) 0 0 205.2 CO2(g) -393.5 -394.4 218.8 H2O(l) -285.8 -237.1 70.0 For each of the following, express your answers to 3 significant figures. Do not include a sign in any of your answers - your answers should be entered as absolute values. How much heat (in kJ) is produced in burning 1 mole of CH4 under standard conditions if reactants and products are brought to 298 K and H2O(l) is formed? kJ What is the maximum amount of useful work (in kJ) that can be accomplished under standard conditions by this system? kJ What is the maximum efficiency of a heat engine burning natural gas?'