An Experiment to Find the Amount of Heat Energy Released When 1g of Candle Wax Burns - page 1
Keywords: An Experiment to Find the Amount of Heat Energy Released When 1g of Candle Wax Burns Chemistry GCSE
By slashwk on 23/11/2006 17:19:06
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 3 pages: 1 2 3
Aim
The aim of this experiment is to discover how much energy is released when we burn 1g of candle wax.
Method
The best way to conduct this experiment is to use the candle as it burns, to heat up water. The reason for this is because we know water’s ‘specific heat capacity’ is. A specific heat capacity is how much energy is required to raise the temperature of 1kg of a material by one degree Celsius. 4200 joules are required to raise 1kg of water by one degree Celsius. We will carry out the experiment in the following way:
• Make sure we measure the mass of the water before the experiment (we can do this by measuring the beaker mass, and taking it away from the mass of the water AND the beaker mass)
• Also make sure we know the mass of the candle (and its holder)
• Then we need to take note of the initial temperature of the water with the thermometer
• Set up the equipment as shown in the Diagram
• Light the candle
• Keep observing the thermometer readings until a significant gain in temperature is noticed and then take note of the mass of the candle and its holder in order to find out the mass of wax burned (by subtracting its mass after the experiment, by its mass beforehand)
Before we undertake the experiment there are some points we must consider. First of all, an aspect of our technique which will greatly vary the results is the fact that the candle’s energy transfer into the water may not be 100% efficient. There are some changes we can make to the experiment to make it more effective. One factor that changes the results is that the further the flame is from the bottom of the beaker, the less energy is going to reach the water. If we put the flame closer to the beaker, even touching it, it will produce better results. Another factor is natural wind currents that can occur inside the room. These currents can blow heat energy away from the flame and also away from the beaker. To prevent this, we could stand up some books around the flame to prevent the currents reaching the flame.
Diagram
Results
Experiment Mass of Water Initial Temp. (ºC) Final Temp.
(ºC) ΔT (Temp. change) Mass of wax burned Calculation Result (kJ per g)
1 85.6 24.5 44.5 20 0.36 4.2x20x85.6
0.36
19.973
2 100 24.5 74.5 50 2.36 4.2x50x100
2.36 8.898
3 31.48 24 43 19 0.29 4.2x19x31.48
0.29 8.662
4 65.9 24 43 19 0.24 4.2x19x65.9
0.24 21.911
5 118.53 23.5 42.5 19 0.72 4.2x19x118.53
0.72 13.137
Conclusion
Our results aren’t very helpful when it comes to drawing a conclusion about how much energy there is in a gram of candle wax. However,
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