Rates of reaction

• Chemical reaction


  Substances are chemically changed into new substances
• Signs of a chemical reaction

  • Solid formed
  • Colour change
  • Effervescence
  • Precipitation
  • Temperature change
  • Odour produced
• Rate of a chemical reaction

  The speed at which the reaction occurs
• Speeding up a chemical reaction

  1. Collide

  2. Increase the number of collisions taking place
• To increase the rate of a chemical reaction

  1. Increase concentration

  2. Increase temperature

  3. Decrease particle size

  4. Suitable catalyst
• Rates of reaction


  Changes taking place in a chemical reaction, such as a change in mass or a change in volume
• Comparing rates of reaction


  Measuring the changes taking place in a chemical reaction
• Changes


  • Change in mass
  • Change in volume
• Comparing changes


  Using a graph
• Steeper slope


  Faster reaction
• Flatter slope


  Slower reaction
• A faster reaction will have a steeper slope
• Same final volume


  The volume of product is the same at the end of the reaction
• Same total volume


  The same quantity of starting material was used
• The only difference may be the concentration, temperature, or the particle size
• Ethyne


  The first member of the alkyne family, with the molecular formula H-C=C-H
• Ethyne can be produced by the reaction of calcium carbide with water
• The table shows the results obtained in an experiment carried out to measure the volume of ethyne gas produced
• Comparing the average rate from a graph


  Using the formulae below: Rate = change in quantity/change in time
• ∆q


  ∆t