Investigating the Efficiency of Fuels.

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Tom Sharp – Chemistry investigation – 11G

Investigating the Efficiency of Fuels

Introduction

        I am going to investigate the efficiency of two fuels. I will carry out an investigation which will allow me to see which fuel is more efficient.

        This is made easy because the fuels I am going to test each burn well through sprit burners. The fuels are reactive, and produce heat, therefore exothermic. You can tell this because when the fuels burn they produce heat, and when heat is produced from a reaction we call it an exothermic reaction.

Energy level diagram showing an Exothermic Reaction:

This shows an exothermic reaction because the products are at a lower energy level than the reactants. The difference in height represents the energy given out in the reaction. The EA is the activation energy, and this is the energy that is needed to break bonds. It is the initial rise in the energy given out in the reaction.

        On this energy level diagram, Delta H is negative.

This is a table showing the energy required to make or break a covalent bond.

The bond energies are measured in kJ. Making for example, a C – H bond, releases 412 kJ of energy. This is an exothermic process, as energy is released and not required.

Diagram

Aim

        In this experiment I will aim to see how much hexane and then pentane is required to boil water starting from 20˚C (average room temp). I will set up the apparatus as show in the diagram and do the experiment, which I will go through on my plan.

        In the preliminary experiment, I did not take any results, but observed the experiment closely so as a smooth running takes place in my final experiment, where I will need to collect a good set of results.

Qualitative observations From the Preliminary Experiment

        Whilst heating the water with hexane, I noticed the flame would often get blown over and it would lean to the side. This meant the heat from the flame was not concentrated on the copper tin, and thus an unfair test for hexane, as that heat energy released from the hexane was lost. I have decided to use Perspex lab shield in order to stop draughts from disturbing the flame.

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        I also noticed that the hexane and pentane bottles are not all the same height. I will have to measure 1cm from the base of the flame to the base of the copper tin. In order to make sure the flame lengths are the same, I will tweak the wick until both flames are roughly 1.5cm each.

Plan

        I will set up apparatus as I did in my preliminary experiment, and make sure I accurately measure 50ml of water for each test. I will also make sure in each test the water is at 20°C. This was the temperature ...

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