Rates of reaction

• Rate of Reaction

  The change in amount of reactant or product with time
• Collision theory


  For substances to react: Their particles must collide, The particles must have enough energy to make the bonds in the reactants break
• Activation energy


  The minimum amount of energy that the particles need to have to react
• Controlled variables


  Things that could change but don't, kept constant by the scientist and allow for a fair test
• Independent variable


  The variable that is changed by the scientist
• Dependent variable


  The variable that is measured
• Fair test


  One in which we only change one factor or variable, all the other variables are kept the same
• Anomalous result


  If one of the results in a set of results is enormously different to the other results, this result is rejected before the average is calculated
• Measuring the rate of reaction

  1. Use a stopwatch by measuring the time taken for the magnesium to disappear

  2. Follow how fast the gas is produced by counting the bubbles of gas produced
• A reaction that takes 10s is faster than one which takes 20s because it happens in a shorter period of time
• Calculating the rate of reaction: Rate = 1/time
• Multiplying the rate by 1000 makes it easier to plot on a graph
• Factors affecting rate of reaction

  • Increasing temperature increases the rate
  • Decreasing the concentration decreases the rate
• Increasing the concentration increases the rate of reaction because there are more particles in the same space, leading to more frequent and successful collisions
• Increasing the temperature increases the rate of reaction because the particles have more energy and move faster, leading to more frequent and successful collisions
• Experimental errors are caused by limitations in the accuracy of instruments, human error, external factors, and using contaminated reagents
• Investigating how concentration affects the rate of reaction


  1. Measure and cut 4 pieces of magnesium ribbon

  2. Add magnesium ribbon to hydrochloric acid and start stopwatch

  3. Stop stopwatch when magnesium disappears and record time

  4. Repeat with different volumes of hydrochloric acid and water
• Using a measuring cylinder is less accurate than using a pipette
• Investigating how temperature affects the rate of reaction


  1. Measure temperature of tap water

  2. Add 5cm3 water and 1/8 vitamin C tablet to test tube, start stopwatch

  3. Turn test tube upside down, stop stopwatch when it explodes

  4. Repeat with iced water and water from 2 water baths
• Chemical engineers are responsible for delivering molecules to consumers, including developing and testing new products, and making products safely and efficiently
• Full fat ghee and magnesium carbonate produced the strongest glue, as shown by the highest number of newtons on the graph
• Other factors to consider before production of the glue include safety and cost of raw materials