Reaction rates

• one advantage and one disadvantage of using a conical flask to compare gas collected.

  advantage - no loss of gas

  disadvantage - small loss of gas
• Factors which affect rate

  Temperature

  Concentration

  Pressure

  Surface area

  Catalysts
• How can we measure the rate?

  Volume of gas produced

  Change in mass

  Colour change

  Precipitate
• In order to react, particles must collide with each other. When they collide they must be in the correct orientation AND must have sufficient energy. If we can make more collisions happen then the rate of reaction will increase
• When the pressure of a gas is increased the molecules of the gas are forced closer together. This effectively increases the concentration of gas particles. Increasing pressure of a gas therefore has the same

  effect as increasing concentrations of solutions – it increases the rate of reaction in the gas phase.
• increasing rate of reaction - Concentration, pressure, surface area, temperature, catalyst
• increasing surface area -

  Increasing surface area means a greater number of reactant molecules are able to collide with the surface increasing the number of successful

  collisions.
• increasing temperature - Increases the rate of reaction by increasing the energy the molecules have therefore increasing the chance of successful collisions
• what is a catalyst - A substance that increases the rate of a reaction without being used up by it
• how does catalyst work - Providing an alternative route with lower activation energy
• Boltzman - We would expect rate to increase with increasing temperature because the number of collisions increases.

  Increasing temperature gives the particles more energy and so more of them have enough energy to react when they collide.
• homogeneous - the state of the reactants and the catalyst is the same
• heterogeneous - the states of the reactants and catalyst are different
• Boltzmann- more particle exceed the activation energy when the temperature increases