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Gatmospheric pressureqreactionh

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Unformatted text preview: for physical changes, KEproducts < KEreactants – surroundings feel hotter after the reaction Classify different chemical or physical changes as exothermic or endothermic. Under constant pressure (e.g. atmospheric pressure), qreaction = H – for endothermic reactions, H is + – for exothermic reactions, H is – CHEM 161 Exam 4 Study Guide 1 nutritional Cal 1kcal 1000 cal bond energy: energy required to break a bond – always positive – Use bond energies provided to calculate a reaction’s H – Use H and bond energies provided to calculate a bond energy 1 kg m 2 kinetic energy (KE): KE= ½mv2 – energy associated with an object’s motion joule (J): 1 J = Fuel values and food values: reported as a positive value in kJ/g or Cal/g. Thermochemical Equations indicate the enthalpy changes as well as reactants and products – Be able to solve stoichiometry problems involving enthalpy changes using a thermochemical equation. Guidelines for Thermochemical Equations 1. The magnitude of H is proportional to the amount of reactants and products in the equation. 2. H is the opposite sign for the reverse reaction. 3. If the coefficients in an equation are multiplied by a factor n, H must able...
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