THERMOCHEMISTRY

• WHAT IS THERMOCHEMISTRY?

  study of heat changes during chemical reactions
• HOW TO REMEMBER DIRECTION OF ENERGY IN BOND FORMATION/ BREAKING?

  BRENDO MEXO
• WHAT IS DONE TO ENERGY TO BREAK BONDS?

  energy put in
• WHAT IS DONE TO ENERGY TO FORM BONDS?

  energy given out
• EXAMPLES OF EXOTHERMIC REACTIONS?

  • combustion
  • neutralisation
  • water and calcium oxide
  • rusting
  • respiration
  • displacement
• EXAMPLES OF ENDOTHERMIC REACTIONS?

  • photosynthesis
  • thermal decomposition
  • cracking alkanes
  • metal carbonate and acid
• WHAT IS AN ENTHALPY CHANGE?

  heat change at a constant pressure
• WHAT ARE STANDARD CONDITIONS?

  100 kPa, 298 K
• WHAT HAPPENS TO SURROUNDINGS IN AN EXOTHERMIC REACTION?

  heat up
• WHAT HAPPENS TO SURROUNDINGS IN AN ENDOTHERMIC REACTION?

  cool down
• WHAT IS TEMPERATURE?

  average KE of particles in a system
• DOES TEMPERATURE DEPEND ON HOW MANY PARTICLES ARE PRESENT?

  no, it is independent of the number of particles present
• HOW IS TEMPERATURE MEASURED?

  with a thermometer
• WHAT IS HEAT?

  measure of total energy of all particles present in a given amount of substance
• DOES HEAT DEPEND ON THE NUMBER OF PARTICLES PRESENT?

  yes, it is dependent of the number of particles present
• WHY IS HEAT DEPENDENT ON THE NUMBER OF PARTICLES PRESENT?

  energy of every particle is included
• WHAT DIRECTION DOES HEAT ALWAYS FLOW?

  high to low temperature