Form 5 Chapter 4 Thermochemistry

Planning of experiment:

1		Different members of this homologous series have different heat of combustion. Table below shows the heat of combustion of some alcohols.
		Alcohol Alcohol Heat if combustion (KJ mol-1) Haba pembakaran (KJ mol-1) Methanol Metanol - 728 Ethanol Etanol - 1376 Propan-1-ol Propan-1-ol -2016 Butan-1-ol Butan-1-ol - 2678
		Plan a laboratory experiment to determine the heat of combustion of alcohols shown in the table. Your planning should include the following aspects:
		(a)                Statement of the problem Pernyataan masalah  (b)              All the variables Semua pembolehubah                        (c)               Hypothesis             Hipotesis                                 (d)              List of materials and apparatus Senarai bahan dan radas (e)               Procedure             Prosedur                                 (f)                Tabulation of data Penjadualan data                   [17 marks] [17 markah] Suggested Answer: Aim To study the heat of combustion of different alcohols . Problem statement Do alcohols with more carbon atoms per molecule have higher value of heat of combustion? Variables MV: Different types of alcohol RV: Heat of combustion FV:   1. Volume of water        2. type of container/size of container Hypothesis Different type of alcohol produces different heat of combustion. Apparatus & Materials A: copper beaker, spirit lamp, thermometer, weighing balance, wooden block, tripod stand, wind shield, measuring cylinder. M: Ethonol, propanol, butanol, water, Procedure: 1. [200 cm3] of water is poured into a [copper] beaker. 2. Initial temperature of the water is recorded. 3. A spirit lamp is half filled with ethanol. 4. Initial mass of the spirit lamp is recorded. 5. Put the spirit lamp under the copper beaker and ignite the wick immediately. 6. Stir the water and the flame is put off after the temperature has increased by 30oC. 7. The highest temperature of the water is recorded. 8. Immediately the final mass of the spirit lamp is recorded. 9. Repeat the experiment by replacing ethanol with propanol and butanol. Tabulation of data Type of alcohol Initial temperature / oC Final temperature / oC Initial mass of spirit lamp / g Final mass of spirit lamp / g Methanol Ethanol Propan-1-ol Butan – 1- ol