2 3 e-Peter A. Rock Ethan Gallogly ed by power plants produce energy by burning

Question

2 3 e-Peter A. Rock Ethan Gallogly ed by power plants produce energy by burning carbon-based fuels, which also produces carbon dioxide Carton dioxide is a greenhouse gas, so over-production can have negative effects on the environment. Use enthalpy of formation data to caiculate the number of moles of CO2g) produced per megajoule of heat released from the combustion of each fuel under standard conditions 1 atm and 25 (a) coal, C(s, graphite) (b) natural gas, CHa(g Number mol MJ mol: MJ (c) propane, C3Hs(g): (d) octane. C8He() (At 250.1 kJ-mor). D mol- Mi mol MJ1 mol: MJl Hint

Explanation / Answer

1.(a) combustion of 1 mole of C (graphite) liberates 393.5 KJmol-1 of heat

Therefore moles of C (graphite) that will liberate 1 MJ (=1000KJ) of heat = 1MJ/393.5 KJ = 1000KJ/393.5 KJ = 2.541 molMJ-1

(b) Combustion of 1 mole of natural gas, CH4 liberates 889 KJmol-1 of heat

Therefore moles of CH4 that will liberate 1 MJ(=1000KJ) of heat = 1MJ/889 KJ =1000KJ/889 KJ

= 1.125 molMJ-1

(c) Combustion of 1 mole of propane, C3H8 liberates 2220 KJmol-1 of heat

Therefore moles of C3H8 that will liberate 1 MJ(=1000KJ) of heat = 1MJ/2220 KJ =1000KJ/2220 KJ

= 0.450 molMJ-1

(d) Combustion of 1 mole of octane (l), C8H18(l) liberates 5.4MJmol-1 of heat

Therefore moles of C3H8 that will liberate 1 MJ of heat = 1MJ/5.4MJ = 0.1852 molMJ-1

Note: The standard enthalpy values may vary marginally with the data given in your text book. Hence to get even more eccurate answer take the datas given in your text book.

2. heat of combustion of ethane = 1560 KJmol-1

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