rates of reaction

• rate


  how quickly something happens; determined by measuring a change + the time taken for that change to happen
• concentration


  • amount of substance per unit volume
  • in a more concentrated solution, there are more reactant particles per unit volume; they are closer together
• pressure


  • Pressure is a measure of how concentrated (or spread out) a force is.
  • the pressure of a gas is related to the amount of particles per unit volume
  • higher pressure means the particles are pushed closer together
• collision theory

  • the energy involved in the collision must be enough to break the chemical bonds in the reacting particles
  • this theory links collisions with rate of reaction
• frequency


  • frequency is a measure of how often something happens
  • if something happens more frequently, it happens more often
• marble chips


  marble is calcium carbonate (CaCO3) and marble chips are small pieces of that compound
• catalyst


  substance that increases the rate of reaction, but is chemically unchanged at the end of the reaction
• reaction profile diagram


  a diagram that shows the changes in energy involved in a chemical reaction
• how do you know if a reaction has taken place? (give 3)

  • change in colour
  • change in mass
  • appearance of a precipitate
• what happens in a chemical reaction?

  one or more new substances are produced
• what is collision theory?

  it is the energy involved in the collision between reacting particles to make them break chemical bonds
• what is activation energy?

  minimum energy required in a collision for a reaction to occur
• what can change the rate of reaction?

  • concentration of a solution
  • temperature
  • surface area of a solid
  • pressure of a gas
  • a catalyst