C3.2 - ENERGETICS

• what is an exothermic reaction?

  energy given out to the surroundings

  • temperature of surroundings increases
  • examples include combustion, oxidation and neutralisation
• what is an endothermic reaction?

  energy taken in from the surroundings

  • temperature of surroundings decrease
  • examples include electrolysis, thermal decomposition and first stages of photosynthesis
• factors that come into play for activation energy?

  energy

  orientation

  number of collisions per second (freqeuency)
• what type of energy level diagram is this?

  A) exo

  B) reactants

  C) products

  D) lower

  
• what is the overall energy change in exothermic reaction?

  negative
• what is the overall energy change in endothermic?

  positive
• what type of energy level diagram is this?

  A) endo

  B) higher

  C) positive

  
• energy is given out in exothermic reactions. how is this shown on a reaction profile?

  the energy of products is lower than the energy of reactants, so there is a negative change in energy. this is represented with a downwards arrow.
• energy is taken in endothermic reactions. how is this shown on a reaction profile?

  energy of products is higher than reactants, so the energy change is positive. this is represented with an upwards arrow
• energy change = energy taken in - energy given out
• negative number means?

  exothermic
• positive number means?

  endothermic