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M olar enthalpy of combustion. c alorimeter. Raw data. Calculation heat released. amount of energy released temperature rise = 89 - 18 = 71 o C mass of fuel burned = 18.62-17.14 = 1.48g heat absorbed by the water = heat released by fuel = mass of water x shc water x temperature rise
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Molar enthalpy of combustion calorimeter
Calculation heat released amount of energy released • temperature rise = 89 - 18 = 71oC • mass of fuel burned = 18.62-17.14 = 1.48g • heat absorbed by the water = heat released by fuel = mass of water xshcwaterx temperaturerise = 100 x 4.2 x 71 = 29820 J (for 1.48g)
Calculation for 1 mole of ethanol • Mr(ethanol) = 46 (H=1, C=12, O=16) • therefore 1.48g ethanol = 1.48/46 = 0.03217 mol • scaling up to 1 mole of ethanol burned gives 29820 x 1 / 0.03217 = 926951 J Answer: molar enthalpy of combustion of ethanol = ΔHc(ethanol) = -927 kJ/mol