C7: Chemical Reactions

Rate of reaction

The rate of reaction is caused by many different factors. They include...

  • Concentration
    • When there is a high concentration of particles, the rate of reaction will increase
    • This is because with more particles, there will be more collisions. This causes to more successful chemical reactions, and therefore speeds up the rate of reaction
  • Surface Area
    • When there is a larger surface area, the rate of reaction will increase
    • This is because with a greater surface area, more particles are exposed to the particles in the other reactant, causing them to have more collisions. This causes to more successful chemical reactions, and therefore speeds up the rate of reaction
  • Temperature
    • When temperature is higher, the rate of reaction will increase
    • This is because higher temperature increases the kinetic energy in particles, which causes more successful collisions. As more particles have energy that is greater than the activation energy (the minimum amount of energy to react into product), the reaction will occur faster
  • Catalysts
    • When there are catalysts present, the rate of reaction will increase
    • Catalysts lower the activation energy (minimum energy required to react), allowing there to be more successful collisions that overcome the activation energy


Redox
  • Redox reactions are reactions where reduction and oxidation happen in the same reaction
  • Oxidation is the process where an element, ion, or compound loses an electron and gains oxygen
  • Reduction is the process where an element, ion, or compound gains an electrons and loses oxygen
  • Elements, ions, and compounds have an oxidation state which states the number of electrons lost or gain (for example, an oxidation state of -2 means that 2 electrons are gained in the reaction and an oxidation state of 1 means that 1 electron is lost)


Oxidising and reducing agents

  • An oxidising agent is a substance which oxidises another substance during a redox reaction
  • A reducing agent is a substance which reduces another substance during a redox reaction
  • For example, in the reaction CuO + H2 →Cu + H2O...
    • The oxidising agent is CuO as it oxidises hydrogen by giving it oxygen
    • The reducing agent is H2 as it takes the oxygen from CuO


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