To quantify the amount of energy produced by different fuels and to determine which fuel is more efficient (has a higher calorific value). Introduction:
The easiest way to achieve our aim is by heating a substance with a known specific heat capacity and using the energy released from burning our fuels. This will give us the value of the heat energy released by the combustion of our two fuels. The chemical reaction for combustion:
FUEL + O2 Heat energy released CO2 + H2O It is the heat energy released that we are concerned with, the amount released in this reaction will provide us with the calorific value for each fuel. Materials and Method
1. All materials and equipment was gathered this included; a calorimeter, crucible, candle (Paraffin wax), matches, teat pipette, boss and clamp, stand, tripod stand and ethanol. 2. Set up the apparatus (see diagram)
3. Measure the weight of the candle the empty crucible, the empty calorimeter and record results. 4. Fill the calorimeter ¾ full of water.
5. Measure the calorimeter containing water.
6. Clamp calorimeter.
7. Measure the initial temperature of water and record.
8. Using the pipette put about a pipettes worth of ethanol into the crucible. 9. Place the crucible on top of the tripod and under the calorimeter and light the ethanol. 10. Put the polystyrene cover over the calorimeter and stir the water gently. 11. When all ethanol has burned out record the highest temperature reading on the thermometer. 12. Record the temperature difference.
13. Do not change the water.
14. Set up the experiment to burn the candle.
15. Re-measure the initial temperature of the water.
16. Light the candle and stir the water gently.
17. Once the temperature has increased by the same amount it increased in the first experiment blow out the candle and weigh the candle. Diagram
Fuel| Initial temperature of water °C| Final temperature of water °C | Mass of fuelKg| Mass of calorimeterX 10 ⁻ᵌ Kg | Mass of waterX 10 ⁻ᵌ Kg| Candle (Paraffin Wax)| 24| 44| 0.64 X 10 ⁻ᵌ| 51.76 X 10 ⁻ᵌ| 102.22x10 ⁻ᵌ| Ethanol| 36| 56| 0.4 X 10 ⁻ᵌ| | |
Table of recorded data.
Heat supplied to the combined calorimeter and water.
Energy given to water = Mass of water x specific heat capacity x (Final temperature – Initial temperature)
Ew = Mw x Cw x ( Tf -Ti)
Ew = 102.22 X 10 ⁻ᵌ x 4200 x (44 - 24)
Ew = 8.568 K J
Energy given = Mass of calorimeter x specific heat capacity x (Final temperature – Initial temperature) to calorimeter
Ec = Mc x Cc x ( Tf -Ti)
Ec = 51.76X10⁻ᵌ x 385 x (56 - 36)
Ec = 3.985 KJ
Calorific value for fuels
Using the data collected from the experiment and the formula below I will find the calorific value for each fuel. CV = Ew + Ec
Mass of fuel
CV = 8.568 KJ + 3.985KJ
0.64 x 10-3 Kg
CV = 19614.063 KJKg-1
Calorific Value of ethanol = 19.6 MJKg-1
Candle (Paraffin Wax)
CV= 8.568 KJ +3.985KJ
0.4 x 10-3 Kg
CV= 31382.5 KJKg-1
Calorific Value of the candle = 31.4 MJKg-1
The theoretical calorific value for ethanol is 29.6 MJKg-1.
The experimental calorific value that we calculated using the results from the experiment is 19.6 MJKg-1. The percentage error is:
Theoretical value - Experimental Value x 100 = percentage error Theoretical value
29.6 MJKg-1 - 19.6 MJKg-1 x 100 = 33% error
Candle (Paraffin wax)
The theoretical calorific value for Paraffin wax is 43.1 MJKg-1. The experimental calorific value that we calculated using the results from the experiment is 31.4 MJKg-1.
The percentage error is:...