Aim: To find out which fuel gives out the most energy.
We will be using 6 different fuels to heat up 100ml of water, and find out the changes of the temperature. We will measure the temperatures of the water before and after the experiment. We will burn heat the water for exactly 2 minutes, and check the changes in temperature. The change in temperature will allow us to work out the energy given off the fuel by using this formula:
Mass of water x 4.2 (water’s specific heat capacity) x temperature change = energy transferred from the fuel to the water
When the fuels are burnt, energy is given off. I will be calculating the energy given off using the formula above. The specific heat capacity is the energy needed (Joules) to heat 1 gram of water by one degrees Celsius. Preliminary Experiment
To help me decide the vital elements of the experiment, I made a trial run using methanol to check if my chosen quantities and set up would work. Results:
Height of can from burner: 5cm
Mass of burner at start = 204.47g. Mass of burner finish = 203.6g. Mass of fuel burned = 0.87g Start temp = 19oC Finish temp = 23oC, Temp rise = 4oC
Following the pilot experiment I made some minor adjustments: Height of can above wick down to 4cm to improve contact with flame and stir the water, because the rise in temperature is too little.
1. Set the experiment up as above
2. Fill the container with 100ml of tap water.
3. Measure the temperature of the water.
4. Weigh the burner before burning.
5. Heat the water for 2 minutes.
6. Record the temperature of the water after 2 minutes. 7. Weigh the burner again and record the change in weight. 8. Repeat the procedures above for the other fuels.
Goggles will be used during the experiment, because it involves glassware and poisonous alcohol. Also, if any alcohol is spilt, all fire would be put off and the alcohol would wiped immediately.
For each test, I am making sure that the beaker/can is the same distance (4cm) to the tip of the fuel burner. Also, I am going to make sure that the wick of the burner is always the same length(1.5cm), this means that the flames are the same size, so the degree of heating is going to be equal. I am going to change the water after every test, so the water always starts at similar temperatures, preventing from falsifying the rising in temperature. I am going to use the same amount of water for each test. Also, I am going to prevent the opening of the burner, because some of the fuels might evaporate, and would affect the weight of the burner. I am going to weigh the burner just before the test, so I could get the accurate weight in case of any evaporation. I am going to use an accurate scale that goes at least to one decimal point, when the burner is not in use, it must be covered to prevent evaporation. Also, the container of water must be the same every time, so the heated surface area is the same. I would repeat each test 3 times to get an accurate result in case if there were any anomalous results.
I predict that the molecule with the most bondings, i.e. Hexanol is going to give off the most energy, because it needs more energy to bond the molecules together, so this means that there are more energy between the bonds. So when the fuel is burnt, the ones with more bondings would give off more energy, so temperature rise would be greater, because more energy is given off by the bondings. When alcohols combust with oxygen/air, they produce heat, So my prediction is that Methanol is going to give off the least energy, and as the bonding gets bigger, the more energy is given off, so Hexanol would give off the most energy. Here are the chemical...
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