# To Find Out Which Fuel Gives Out the Most Energy.

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Introduction

Fuels Investigation Aim: To find out which fuel gives out the most energy. Planning 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.

Middle

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 formulas and the balanced equations: Methanol - CH3OH + 3O2 Ethanol - C2H5OH Propanol - C3H7OH Butanol - C4H9OH Pentanol - C5H11OH Hexanol - C6H13OH The energy given off per mole can be worked out theoretically with the energy per mole for each bonding. Types of bonding Energy in bond (kilojoules per mole) C - C 348 KJ C - H 412 KJ C - O 360 KJ C = O 805 KJ O - H 463 KJ O = O 498 KJ The balance equations and theoretical energy given off: - Methanol 2CH3OH + 3O2 ? 2CO2 + 4H2O 6 x C-H (412) + 2 x C-O (360) + 3 x O-H (463) + 3 x O=O (498) ? 4 x C=O (805) + 8 x H-O (463) = 5612 - 6924 = -1312KJ/Mole Ethanol C2H5OH + 3O2 ?

Conclusion

Rise in temperature of water (°C) Energy released per gram of fuel (j) 1st 0.52 24 19385 2nd 0.49 16 13714 3rd 0.47 14 12511 4th - - - Average 0.49 27 15203 Pentanol Mass of fuel burnt (g) Rise in temperature of water (°C) Energy released per gram of fuel (j) 1st 0.31 9 12194 2nd 0.37 9 10216 3rd 0.34 9 11118 4th - - - Average 0.34 9 11176 Hexanol Mass of fuel burnt (g) Rise in temperature of water (°C) Energy released per gram of fuel (j) 1st 0.31 9 12194 2nd 0.43 13 12698 3rd 0.36 12 14000 4th - - - Average 0.37 11.3 12964 Energy Per Mole I am going to use the average energy per gram to work out the energy per mole. Methanol - Formula mass: 32 5811J/gram x 32 = 185952J/mole = 185.95KJ/mole Ethanol - Formula mass: 46 10812J/gram x 46 = 497352J/mole = 497.35KJ/mole Propanol - Formula mass: 60 13864J/gram x 60 = 831840J/mole = 831.84KJ/mole Butanol - Formula mass: 74 15203J/gram x 74 = 1125022J/mole = 1125KJ/mole Pentanol - Formula mass: 88 11176J/gram x 88 = 983488J/mole = 983.5KJ/mole Hexanol - Formula mass: 102 12964J/gram x 102 = 1322328J/mole = 1322.3KJ/mole

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