Chemistry

• What is the definition of activation energy?

  The minimum energy to start a reaction
• What are bond energies?

  Energy required to break 1 mole of a bond
• What type of process is bond breaking?

  It is an endothermic process
• What type of process is bond making?

  It is an exothermic process
• What is a reaction profile?

  A diagram showing energy variation of reactants and products
• What is a cell in chemistry?

  Two electrodes in an electrolyte generating electricity
• What is a battery?

  Two or more chemical cells connected together
• What is an electrolyte?

  A liquid containing ions that conducts electricity
• What is a fuel cell?

  A chemical cell with a continuous supply of reactants
• What is combustion?

  A chemical reaction that releases energy
• What is neutralisation?

  A reaction between an acid and a base
• What is thermal decomposition?

  A reaction where a compound breaks down due to heat
• What is photosynthesis?

  A process where plants convert light into energy
• What are the steps for energy change calculation?

  1. Add bond energies of reactants (energy in)
  2. Add bond energies of products (energy out)
  3. Calculate energy change: energy in - energy out
• What are the pros and cons of alkaline cells?

  Pros:

  • Cheaper to manufacture
  • Can be recharged many times

  
  

  Cons:

  • May end up in landfill sites once discharged
• What are the pros and cons of hydrogen fuel cells?

  Pros:

  • No moving parts
  • Water is the only chemical product

  
  

  Cons:

  • Expensive to manufacture
  • Hydrogen is flammable