Simple Calorimetry to Find the Enthalpy of Combustion of Alcohols

Title: Simple calorimetry to find the enthalpy of combustion of alcohols

I Object:

To find the enthalpy of combustion of ethanol, propan-1-ol and butan-1-ol.

II Data, calculation and results:

Data:

Ethanol:

|initial water temperature |24.0oC |

|final water temperature |44.0oC |

|change in temperature |20.0oC |

|initial mass burner + ethanol |162.837g |

|final mass burner + ethanol |162.133g |

|mass ethanol used |0.704g |

Propan-1-ol:

|initial water temperature |23.0oC |

|final water temperature |44.0oC |

|change in temperature |21.0oC |

|initial mass burner + propan-1-ol |150.033g |

|final mass burner + propan-1-ol |149.039g |

|mass propan-1-ol used |0.994g |

Butan-1-ol:

|initial mass burner + butan-1-ol |181.245g |

|final mass burner + butan-1-ol |180.405g |

|mass butan-1-ol used |0.840g |

|initial water temperature |24.0oC |

|final water temperature |44.8oC |

|change in temperature |20.8oC |

Calculation:

Assume that all the energy from the burning fuel is transferred to the water.

Ethanol:

a. Calculate moles (n) of fuel used

molecular mass (MM) of ethanol = 46

mass ethanol used = 0.704 g

n = mass ÷ MM = 0.704 / 46 = 0.0153 mol

b. Calculate energy required to change temperature of water

energy = mc△T

= 100 x 4.184 x 20.0

= 8.368 kJ

c. Calculate the enthalpy of combustion of ethanol

8.368 ÷ 0.0153

= -547 kJ mol-1

△H ˚c (from experiment) = -547 kJ mol-1

△H ˚c (from literature) = -1367 kJ mol-1

Experimental error = [-547- (-1367)] / -1367 x...