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Tham khảo sách 'chemistry part 9, julia burdge,2e (2009)', khoa học tự nhiên, hoá học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 188 CHAPTER 5 Thermochemistry 5.79 5.80 5.81 A 44.0-g sample of an unknown metal at 99.0 C was placed in a constant-pressure calorimeter containing 80.0 g of water at 24.0 C. The final temperature of the system was found to be 28.4 C. Calculate the specific heat of the metal. The heat capacity of the calorimeter is 12.4 J C. A student mixes 88.6 g of water at 74.3 C with 57.9 g of water at 24.8 C in an insulated flask. What is the final temperature of the combined water 5.82 5.83 5.84 5.85 5.86 5.87 5.88 Producer gas carbon monoxide is prepared by passing air over red-hot coke e io2 g --------- co g Water gas a mixture of carbon monoxide and hydrogen is prepared by passing steam over red-hot coke C s H2O g ------- CO g H2 g For many years both producer gas and water gas were used as fuels in industry and for domestic cooking. The large-scale preparation of these gases was earned out alternately that is first producer gas then water gas and so on. Using thermochemical reasoning explain why this procedure was chosen. Compare the heat produced by the complete combustion of I mole of methane CH4 with a mole of water gas 0.50 mole H and 0.50 mole CO under the same conditions. On the basis of your answer would you prefer methane over water gas as a fuel Can you suggest two other reasons why methane is preferable to water gas as a fuel The so-called hydrogen economy is based on hydrogen produced from water using solar energy. The gas is then burned as a fuel 2H2 g O2 g ------- 2H2O Z A primary advantage of hydrogen as a fuel is that it is nonpolluting. A major disadvantage is that it is a gas and therefore is harder to store than liquids or solids. Calculate the number of moles of H2 required to produce an amount of energy equivalent to that produced by the combustion of a gallon of octane CgH18 . The density of octane is 2.66 kg gal and its standard enthalpy of formation is 249.9 kJ mol. Ethanol C2H5OH and gasoline assumed to be all octane C8H 8 are both used as .
