Energetics Experiment Essay

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Energetics Aim: To measure the energy released from the complete combustion of a known mass of alcohol or paraffin wax, to heat water. Hypothesis: The combustion of alcohols is exothermic. In this experiment the energy is released from burning a known mass of alcohol in order to heat a known amount of water. A comparison of various alcohols and paraffin wax (methanol, ethanol, propanol, butanol, octanol and candle) as fuels can be made by calculating the quantity of energy transferred to the water. In this experiment, the amount of energy (heat) involved in a chemical change will be determined. When alcohol burns it produces carbon dioxide and water as products. Energy is also released in the reaction. The alcohols that will be used are, methanol CH3OH, ethanol CH3CH2OH, propanol CH3(CH)2OH, butanol C4H9OH, octanol C8H18O, and paraffin wax C25H52. The heat obtained when a known mass of alcohol or paraffin wax burns will be used to warm a measured volume of water. Enthalpy change can be defined as the amount of heat released or absorbed when a chemical reaction occurs at constant pressure. In an exothermic reaction, such as the case in this experiment, the following reaction takes place: H = H(products) - H(reactants) = negative (-ve) Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The relationship between heat and temperature change is usually expressed, where c is the specific heat. The relationship does not apply if a phase change is encountered, because heat added or removed during a phase change does not change the temperature. The graph below demonstrates the structural diagrams of the fuels used. They are arranged in ascending order of heat released upon complete combustion: Fuels Structural Diagram Description Methanol 1 carbon atom 4 hydrogen atoms Ethanol 2

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