rates of reaction

• what is the rate of a chemical reaction?

  how fast the reactants are changed into products
• what is an example of a slow reaction?

  rusting
• what is an example of a fast reaction?

  burning
• the steeper the line on the graph the faster the rate of reaction but overtime the line will become less steep due to the reactants being used up
• particles must collide with enough energy in order to react
• what does the rate of reaction depend on?

  1. temperature
  2. the concentration of the solution or the pressure of gas
  3. surface area
  4. the presence of a catalyst
• what increases the rate of reaction?

  more collisions
• why does increasing pressure or concentration increase rate of reaction?

  more particles to collide frequently
• why would increasing surface area increase the rate?

  if one of the reactants is a solid, then breaking it up into smaller pieces will increase its surface area to volume ratio. this means that the particles around it will have more area to work on so more frequent collisions
• what practices can be used to measure rates of reaction?

  1. precipitation and colour change
  2. change in mass
  3. the volume of gas given off
• what is the happens in the practical precipitation and colour change?

  -you can record a visual change in a reaction if the initial solution is transparent and the product is a precipitate which clouds the solution. you observe a mark at the bottom of the beaker and measure the time it takes for it to disappear
• what happens in the change of mass where a gas is released practicle?

  -you add a beaker on top of a balance. as the gas is released the mass disappearing is measured and the quicker the reading drops means the faster the reaction. measure the readings of the time and mass to plot on a graph
• what happens in the volume of gas given of practicle?

  a gas syringe is used to measure the volume of gas given off, the more gas given off the faster the reaction