ENERGETICS_CORE(MAH)_(NXPowerLite) Opp

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ENERGETICS CORE ENERGETICS CORE LEVEL LEVEL
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Topic 5: Energetics (8 hours) 5.1 Exothermic and Endothermic Reactions (1h) 5.1.1 Define the terms exothermic reaction, endothermic reaction and standard enthalpy change of reaction ∆H Θ Standard enthalpy change is heat transferred under standard conditions—pressure 101.3 kPa, temperature 298 K . Only ∆H can be measured, not H for the initial or final state of a system . 5.1.2 State that combustion and neutralization are exothermic processes. Combustion of organic compounds are good examples of exothermic reactions. 5.1.3 Apply the relationship between temperature change, enthalpy change and the classification of a reaction as exothermic or endothermic. 5.1.4 Deduce, from an enthalpy level diagram, the relative stabilities of reactants and products and the sign of the enthalpy change for the reaction. If the final state is more stable (lower on the enthalpy level diagram), this implies that Hfinal < Hinitial and ∆H must be negative. Energy must be released in going to a more stable state.
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Energy Changes and Chemical Reactions Very often chemical changes are accompanied by changes in the heat content (enthalpy, H) of the materials which are reacting. This is H. The two diagrams below show the way in which the heat content of a set of reactants changes as they form products. Label one as an exothermic reaction and the other as an endothermic reaction . Label the amount of energy (ΔH or change in heat / change in enthalpy) that would be given out (-) or taken in (+) as the reaction happens. Write on each diagram whether the temperature of the reaction surroundings (eg air or water, if the reactants are in solution) goes up or down as the reaction occurs. Give two examples of an exothermic reaction that you have met in chemistry
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When an exothermic reaction occurs, the products have more/less energy content than the reactants. The heat enegry lost / gained by the reactants is given to other reacting particles / the surroundings ( which can be air or the water used to make aqueous solution). This means the reacting particles are more / less stable than the product.The sign of H in this case is positive / negative . Standard Conditions In comparing enthalpy changes it is essential to ensure the conditions of the system are the same before and after the reaction because ΔH is affected by temperature, pressure and concentration of solutions. The standard conditions for temperature and pressure are _______ and _________ respectively. The substances involved must also be in their normal physical states. Any enthalpy change measured under these conditions is described as a standard enthalpy change of reaction, ΔH Θ 298 .
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5.2 Calculation of Enthalpy Changes (3h) 5.2.1 Calculate the heat change when the temperature of a pure substance is changed Students should be able to calculate the heat change for a substance given the mass, specific heat and temperature
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This note was uploaded on 11/17/2011 for the course PHYS 121 taught by Professor Burgeson during the Fall '11 term at BYU.

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ENERGETICS_CORE(MAH)_(NXPowerLite) Opp - 100s of free ppts...

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