Kinetics

• Exothermic reactions


  chemical energy → heat energy
• Endothermic reactions 


  heat energy → chemical energy
• Examples of exothermic reactions


  burning fuels, neutralisation, displacement
• Why is the reaction exothermic

  because more energy is released making bonds in products than is needed to break bonds in reactants
• example of endothermic reaction

  decomposition reactions
• why is the reaction endothermic

  because more energy is needed to break the bonds in the reactants than making the bonds in products
• equation for energy change

  break- make
• Define enthalpy

  Heat energy change at a constant pressure
• catalyst 


  a substance which speeds up a reaction by lowering the activation energy through finding an alternative reaction route without getting used up in the reaction
• standard enthalpy change 


  the heat change when a chemical reaction occurs at a constant pressure of 100kPa
• standard enthalpy change of combustion 


  the enthalpy change when 1 mole of substance burns completely in oxygen where all reactants and products are in their standard states
• enthalpy of neutralisation 


  the enthalpy change when 1 mole of water is formed from its ions in a dilute solution
• enthalpy of neutralisation equation 


  H+ (aq) + OH- (aq) →H2O (l)
• enthalpy of neutralisation equation 


  q= m * c * ∆T
• moles with concentration equation

  n= c*v
• mean bond enthalpy 


  the energy required to break 1 mole of a particular covalent bond bond, measured in its gaseous state, averaged across many compounds containing the bond
• Hess' law


  the enthalpy change for a chemical reaction will be the same, whatever route is taken from the reactants to the products
• hess' law equation 


  ∆H1= ∆H2+ ∆H3
• enthalpy change of formation

  the enthalpy change when 1 mole of compound is made from its constituent elements under standard conditions, where all reactants and products are in their standard states
• Rate of reaction


  change in concentration in a given time
• rate= k[A][B]
• what is K


  rate constant
• what affects k


  temperature
• What must particles do in order to react?

  Collide with sufficient energy and correct orientation
• Do most collisions result in a reaction?

  No
• What is Activation Energy?

  The minimum energy for a reaction to occur
• What does a labelled Maxwell-Boltzman Curve include?

  • Average energy
  • Activation energy
  • Most probable energy
  • Effect of increasing temperature