c5 - energy changes

• forming a bond is an exothermic reaction
• Energy is stored in chemical bonds.
• Activation energy is the minimum amount of energy the reactant particles require in order to collide with each other and react.
• The term 'bond energy' refers to the amount of energy required to break one mole of a particular covalent bond.
• activation energy is the minimum amount of energy needed for particles to react
• reaction profile is a graph which shows the relative energies of reactants and product, as well as activation energy of the reaction
• reaction profiles show energy changes
• chemical reactions take place when the reacting particles collide with sufficient energy
• the energy released from forming new bonds is greater than the energy needed to break existing bonds
• the energy needed to break existing bonds is greater than the energy released from forming new bonds
• during a reaction energy must be supplied to break reactant bonds and energy is released when products' bonds are formed
• conservation of energy - overall amount of energy does not change
• exothermic reaction - energy is transferred to the surroundings : temperature of the surroundings increases
• endothermic examples : thermal decomposition
• endothermic everyday uses : sports injury pack
• exothermic reaction examples - oxidation reactions, combustion and neutralisation
• overall energy change = total energy of reactants - total energy of products
• energy is stored in chemical bonds
• during a chemical reaction, the bonds of the product must be formed
• Activation energy is the minimum amount of energy the reactant particles require in order to collide with each other and react.
• different chemical bonds hold different amounts of energy
• an exothermic reaction produces a negative energy change
• the term bond energy refers to the amount of energy required to break one mole of a particular covalent bond
• forming a bond is an exothermic process
• bond energy values are always positive
• an endothermic reaction produces a positive energy change value
• If the reactant molecules in a reaction have more energy in their chemical bonds than the product molecules energy will be released
• breaking bonds is an endothermic reaction
• what is a cell?

  A cell is composed of two electrodes dipped in a an electrolyte solution. It produces electricity from a chemical reaction