Essay Molar Heat of Combustion of Alkanols (Hsc Chem)

2047 WordsJul 19, 20109 Pages
Molar Heat of Combustion Aim: To find the molar heat of combustion for four different alkanols: 1. Methanol 2. Ethanol 3. 1-Propanol 4. 1-Butanol - And to compare the experimental value with the theoretical. Background: The Molar Heat of Combustion of a substance is the heat liberated when 1 mole of the substance undergoes complete combustion with oxygen at standard atmospheric pressure, with the final products being carbon dioxide gas and liquid water. (Ref. “Conquering Chemistry, Roland Smith, 2005”) The Heat Capacity of a substance is the amount of heat energy it must consume in order to raise its temperature by 1 Kelvin or 1° Celsius. The heat capacity of 1 mol of a pure substance is known as its molar heat capacity, which…show more content…
Used the formula ‘q = mCΔT’ to calculate the heat/energy produced, (for each trial, then the average was found). 17. Calculated Molar heat of combustion, (using the two averages previously calculated) and comparing this value with the theoretical value. 18. Steps 15 – 17 were repeated for each alkanol. Results: All Measurements have an uncertainty of ‘+/- 0.05’ for both the mass (in grams) and the temperature (in degrees Celsius). Methanol Trial Mass of can (g) Mass: can + water (g) Mass – Spirit Burner (g) (+/- 0.05g) Temperature (°C) (+/- 0.05°C) Start End Difference Start End Difference 1. 78.2 178.3 208.4 207.4 1.0 17 40.5 23.5 2. 78.2 178.4 207.4 206.1 1.3 17 39 22 3. 78.2 178.3 206.1 205.1 1.0 17 39.5 22.5 Ethanol Trial Mass of can (g) Mass: can + water (g) Mass – Spirit Burner (+/- 0.05g) Temperature (°C) (+/- 0.05°C) Start End Difference Start End Difference 1. 78.2 178.3 245.6 244.8 0.8 18 40.5 22.5 2. 78.2 178.4 244.8 244.1 0.7 17.5 40.5 23 3. 78.2 178.2 244.1 243.4 0.7 18 41 23 1-Propanol Trial Mass of can (g) Mass: can + water (g) Mass – Spirit Burner (+/- 0.05g) Temperature (°C) (+/- 0.05°C) Start End Difference Start End Difference 1. 78.2 178.2 217 216.3 0.7 18 39.5 21.5 2. 78.2 178.3 216.3 215.7 0.6 18.5 40 22 3. 78.2 178.4 215.7 215.1 0.6 18.5 41 22.5 1-Butanol Trial Mass of can (g) Mass: can + water (g) Mass – Spirit Burner (+/- 0.05g) Temperature (°C) (+/- 0.05°C) Start End Difference Start

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