Energetic

• Bonds have to be ___ and new bonds ___


  Brocken

  Formed
• Bonds breaking is ___


  Endothermic
• Bonds making is ___

  Exothermic
• Activation energy


  The minimum energy required for a reaction to take place, it is the energy required to break the bonds in the reactants
• Enthalpy change symbol


  ∆H
• Enthalpy change


  The total energy change for a reaction
• Exothermic reactions have ____


  More energy that the products
• Endothermic reactions have ____


  Less energy that the products
• Breaking bonds ___ energy (H-H —> 2H)

  Uses
• Making bonds ___ energy (2H —> H-H)

  Releases
• ∆ means?


  Change
• Energy change equation


  Energy change = energy of bond breaking - energy of bond making
• Why are certain reactions exothermic?

  Because more energy is released making bonds that is needed to break bonds in reactants
• Why are certain reactions endothermic?


  Because more energy is needed to break bonds in reactants then is released making bonds in a product
• Negative energy change means

  Exothermic reaction
• An exothermic reaction is ___

  A chemical reaction that releases energy by light or heat
• Exothermic word equation


  Reactants —> Product + Energy
• What happens to exothermic surroundings?

  Heat energy is transferred to your hands so the beaker feels warm or it is transferred to the liquid in the thermometer causing it to expand so the temperature reading increases

  
  

  Heat energy is lost to the surroundings.
• Energy of products and reactants (exothermic)


  In the reaction A+B —> C+D the enthalpy of the products (C+D) is smaller than the enthalpy of the reactants (C+D)
• Examples of exothermic reactions


  - Oxidation for fuels (combustion)

  - Oxidisation of glucose (respiration)
• What does endothermic mean?


  The process describes a process or reaction in which the system absorbs energy from it's surroundings; usually but not always in the form of heat
• Energy of products and reactants (endothermic)

  In reaction A+B —> C+D the enthalpy of the products (C+D) is grater than the enthalpy of the reactants (A+B)
• What happens to the surroundings in a endothermic reaction?

  Heat energy is transferred from your hand to the surroundings so the beaker feels cold or it is transferred from the liquid in the thermometer causing it to contrast so the temperature reading decreases.

  
  

  Heat energy is gained from the surroundings
• Examples of endothermic reactions


  - Thermal decomposition

  - Photosynthesis
• What are energy changes

  - The bond energy is a measure of the amount of energy needed to break apart 1 mole of the stated bond

  - The unit used are KJ/mol
• What is an exothermic reaction?

  Is 1 which gives out energy to the surroundings, usually in the form of heat and usually shown as a rise in temp of the surroundings
• What is a endothermic reaction?


  Is 1 which takes energy form the surroundings, usually in the form of heat and usually shown by a fall in temp in the surroundings