Many power plants produce energy by burning carbon‑based fuels, which also produces carbon dioxide. Carbon dioxide is a greenhouse gas, so over‑production can have negative effects on the environment. Use enthalpy of formation data to calculate the number of moles of CO2(g) produced per megajoule of heat released from the combustion of each fuel under standard conditions (1 atm and 25 ∘C). coal, C(s, graphite) mol⋅MJ−1 natural gas, CH4(g) mol⋅MJ−1 propane, C3H8(g) mol⋅MJ−1 octane, C8H18(l), ΔH∘f=−250.1 kJ⋅mol−1 mol⋅MJ−1