Chemistry, 7: Chemical reaction

Cards (25)

  • When the speed of a reaction is fast, it has a high rate of reaction and a short completion time
  • When the speed of a reaction is slow, it has a low rate of reaction and a long completion time.
  • Collision theory theorises that for a chemical reaction to occur, particles must collide. Energy from collision will be enough to break chemical bonds.
  • Different reactants have different activation energies that acts as a barrier to the reaction.
  • The bigger the activation energy, the slower the reaction will be at a particular temperature as a smaller proportion of collisions will be effective.
  • The rate of reaction will change as the reaction takes place.
  • The rate of reaction can be calculated from the gradient of a curve.
    At its steepest, is the highest gradient, therefore the highest rare of reaction as there is a maximum number of reacting particles present and no. of effective collisions per second is at its greatest.
    When it is not as steep, it has a lower gradient, therefore a lower rate of reaction as there are fewer reacting particles present therefore number of effective collisions per second is lower.
    If gradient is 0, the reaction is complete and at least one of the reactants have been completely used up.
  • What can change the rate of a reaction?
    Concentration of the solution
    Temperature
    Particle size (solid)
    Catalyst
  • How does concentration increase rate of reaction?
    There is a higher number of ions per centimeter cube, therefore more ions available for collisions and thus an increase in successful collisions per second
  • How does temperature increase rate of reaction?
    By increasing the temperature, there will be an increase in kinetic energy. This allows the particles to move faster, and have more frequent collisions, increasing the probability of successful collisions.
  • How does particle size increase rate of reaction?

    Decreasing particle size will increase the surface area of a solid reactant, allowing for more exposed site for reactant particle to bump into it with. This increases the frequent collisions, allowing for more successful collisions.
  • How does a catalyst increase the rate of reaction?

    Catalysts provides an alternative pathway, with a lower activation energy. The lower activation energy means it takes less overall energy to break the bonds, and thus collisions become more effective.
  • Whenever anything burns, oxidation takes place between the fuel and oxygen in the air.
  • Oxidation is when oxygen is added to the element or compound.
  • What is an example of oxidation?

    2Cu + O2 -> 2CuO
    Copper has become oxidised
  • Reduction is the removal of oxygen from a compound
  • What is an example of reduction?

    CuO + Zn -> ZnO + Cu
    Copper (II) oxide has been reduced
    Zinc has been oxidised
  • The reducing agent reduces the compound of oxygen
  • The oxidising agent oxidizes a compound or element with oxygen
  • Oxidation is the loss of electrons
  • Reduction is the gain of electrons
  • The ion charge reversed shows how many electrons an atom loses or gains when it forms a chemical bond
  • Oxidation stat of an element is always 0
  • Oxidation occurs when oxidation state increases
  • Reduction occurs when oxidation state decreases