Energy Changes 0.0 / 5 ? ChemistryEnergy of reactions/Exothermic and endothermic reactionsGCSEAQA Created by: SeapieCreated on: 01-05-17 14:08 what happens if the products store more energy than the reactants they must have taken in more energy from their surroundings, making it an Endothermic reaction 1 of 14 what happens if the products store less energy than the reactants they must transfer excess energy to their surroundings, making it an Exothermic reaction 2 of 14 Examples of Exothermic reactions Combustion(buring fuels), Neutralization(acid+alkalior metal), many oxidation reactions like sodium+water 3 of 14 Uses of Exothermic Reactions reusable Hand warmers use Crystallization of a supersaturated solution, like sodium ethanoate with a catalyst. Self heating cans 4 of 14 Examples of Endothermic reactions Thermal decomposition (CaCO3->CO2+CaO), Citric acid and Sodium hydrogencarbonate 5 of 14 Uses of Endothermic Reactions Sport injury cool packs usually contain Ammonium nitrate+Water, Chill cans of drinks 6 of 14 What is Activation Energy it is the minimum amount of energy needed befor colliding particles of reactants have enough energy to start a reaction 7 of 14 is Bond Breaking Endothemic yes, Bond Breaking Absorbs energy. Bond Making Releases energy 8 of 14 What happens when chemicals react first the bonds between atoms and ions are broken, then new chemical bonds are formed to make products 9 of 14 What directions do the arrows point in Exo/Endo reactions EXOthermic reactions arrow points DOWN. ENDOthermic reactions arrow points UP 10 of 14 What is Bond energy the energy needed to break the bonds between 2 atoms, measured in kJ/mol 11 of 14 How do you calculate energy changes Calculate energy needed to break bonds in reactants, Calculate energy released from making bonds in products 12 of 14 The energy needed to Break and Make the bonds are The same, True or False True 13 of 14 How do you work out overall energy changes energy needed to break bonds - energy needed to make new bonds, if answer is - it is an Exothermic reaction 14 of 14
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