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For this experiment I have been given a task to determine which is the best Alcohol from its Homologous series. I can determine this by finding the Enthalpy change of Combustion for Alcohols.

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Introduction

As Level Chemistry Coursework PLANNING INRODUCTION For this experiment I have been given a task to determine which is the best Alcohol from its Homologous series. I can determine this by finding the Enthalpy change of Combustion for Alcohols. I know that 4.2J of energy is required to raise the temperature of 1g of water by 1�C and to find the Enthalpy change for the Alcohols, I will use the formula D = M/V. The density of water is 1 and therefore 1g is equivalent to 1 ml. APPARATUS The apparatus that I will use within this experiment will consist of: * 6 * 250ml Steel Crucibles * 2 * 100ml measuring cylinders * 6 * 250ml Sprit burners * Clamp + Clamp stand * 2 * Cardboard shields * Stopwatch * 30cm Ruler stick * Electrical weigh I will also include 100ml of six Alcohols from their functional groups. ALCOHOLS BEING USED DIAGRAM FAIR TEST & FACTORS THAT I NEED TO CONTROL For this experiment to proceed successfully, I have to consider some key factors that need to be controlled in order for this experiment to be a fair test. Firstly, the quantity of the Alcohols needs to be the same throughout the experiment. This is because if the quantity is varied, then the results that I receive at the end of the experiment will also be affected. ...read more.

Middle

Alcohols are known to be dangerous chemicals, so it is important that they are not it contact with the user. Thirdly, place the sprit burner beneath the cubicle and light the wick using a light from the Bunsen. While the wick is still burning, Start the stopwatch and using both cardboard shields, grasp them around the sprit burner tightly similarly to a cubical shape to prevent heat loss. This is because the experiment will be affected if most of the heat energy escapes and suffienct amounts of heat energy can only be used to heat the water. Keep the shields held tightly together until 3 minutes are over. I decided to time the experiment for a specific time length because then it helps in comparing the Alcohols. Repeat the experiment for all the alcohols until left with 2 sets of results for each Alcohol. This helps in identifying any mistakes. ANNALYSING RESULTS 1 ALCOHOL Weight of bottle (g) Weight of bottle&fuel Temperature of water (start)(�C) Temperature of water (end) Weight of sprit burner(end) Methanol 238.9 257.2 21 49 256.1 Ethanol 223.6 251.7 21 46 246.0 Propan-1-ol 201.3 223.6 21 51 222.8 Butan-1-ol 239.6 289.7 21 60 288.1 Butan-2-ol 198.7 233.9 21 62 232.0 2-Methyl-Propan-2-ol 204.1 247.3 21 40 245.6 RESULTS 2 ALCOHOL Weight of bottle (g) ...read more.

Conclusion

- -18900 KJ Mol -1 (?H3) = -10500 KJ Mol -1 The experiment proceeded successfully but there were some key factors that may have affected the results. Suitability of experimental procedures There are some factors in the experiment that can be improved if the experiment was repeated. Firstly, the weigh in machine was not suitable for this experiment because it weighed substances to one decimal point (e.g. 2.5) and can be made more accurately by using a weigh that weighs up to four decimal places. Secondly, the experiment was performed in a container with poor insulation and therefore some of the heat may have escaped. If I had the chance to repeat the experiment, I would perform the experiment in a closed insulated container such as a Bomb Calorimeter. This could then minimise the chance of any errors occurring within the experiment. Anomalous Results According to the results that I received, there were no anomalous results but I would repeat the experiment just to be sure that there were no anomalous results. Sources of error There may have been a number of errors within this experiment that could have been avoided. Firstly, the mass of Calcium Oxide and Calcium Carbonate should have been kept the same to allow the experiment to be a fair test. Also, a more accurate thermometer could have been used to determine the temperature change ...read more.

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