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Mark Scheme
PEKA Chemistry Form 5
Experiment No : ......4.1............
Topic: Thermochemistry
Aim To determine the heat of combustion for alcohols
Problem statement Does alcohol with a higher number of carbon atoms per molecule have a higher heat of combustion?
[ K1PP1(i) - Able to write the aim or problem statement correctly]
Hypothesis The higher the number of carbon atoms in the alcohol molecules, the higher is the heat of combustion.
Variables Manipulated variable : Different types of alcohols Responding variable : Heat of combustion Fixed variables : Volume of water, copper can, thermometer
[ K1PP1(ii) - Able to write the hypothesis or variables correctly]
Materials ethanol, propanol, butanol, water
Apparatus Copper can, tripod stand, thermometer, 100 cm3 measuring cylinder, spirit lamp, weighing balance, wooden block, wind shield
[ K1PP1(iii) - Able to list all the materials and apparatus correctly]
Procedure 1. Using a measuring cylinder, 200 cm3 of water is measured and poured into a copper can. 2. The copper can is placed on a tripod stand. 3. The initial temperature of the water is measured and the readind is recorded. 4. 50 cm3 of methanol is poured into a spirit lamp and then weighed. The mass is recorded. 5. The wick of the lamp is lighted up. 6. The water is stirred continuosly until the water temperature is increased by about 30oC. 7. The flame is put off and the highest temperature of water is recorded. 8. The lamp and its content is weighed immediately and its reading is recorded. 9. Steps 1 to 8 are repeated using other alcohols like ethanol, propanol and butanol
PEKA Chemistry Form 5
Experiment No : ......4.1............
Topic: Thermochemistry
Aim To determine the heat of combustion for alcohols
Problem statement Does alcohol with a higher number of carbon atoms per molecule have a higher heat of combustion?
[ K1PP1(i) - Able to write the aim or problem statement correctly]
Hypothesis The higher the number of carbon atoms in the alcohol molecules, the higher is the heat of combustion.
Variables Manipulated variable : Different types of alcohols Responding variable : Heat of combustion Fixed variables : Volume of water, copper can, thermometer
[ K1PP1(ii) - Able to write the hypothesis or variables correctly]
Materials ethanol, propanol, butanol, water
Apparatus Copper can, tripod stand, thermometer, 100 cm3 measuring cylinder, spirit lamp, weighing balance, wooden block, wind shield
[ K1PP1(iii) - Able to list all the materials and apparatus correctly]
Procedure 1. Using a measuring cylinder, 200 cm3 of water is measured and poured into a copper can. 2. The copper can is placed on a tripod stand. 3. The initial temperature of the water is measured and the readind is recorded. 4. 50 cm3 of methanol is poured into a spirit lamp and then weighed. The mass is recorded. 5. The wick of the lamp is lighted up. 6. The water is stirred continuosly until the water temperature is increased by about 30oC. 7. The flame is put off and the highest temperature of water is recorded. 8. The lamp and its content is weighed immediately and its reading is recorded. 9. Steps 1 to 8 are repeated using other alcohols like ethanol, propanol and butanol