rates of reaction

• What does the rate of a reaction measure?

  How fast reactants turn into products
• Can the rate of a reaction be fast or slow?

  Yes, it can be fast or slow
• What is the equation for the rate of reaction?

  $\text{Rate of reaction} =$$\frac{\text{Change in amount of reactant or product}}{\text{Time taken}}$
• What are the units for rate of reaction?

  g/s, cm³/s, mol/s
• What are the methods for measuring the rate of reaction?

  1. Measuring Mass Loss (Gas Produced)
  2. Measuring Volume of Gas Produced
  3. Disappearing Cross (Color Change)
• How do you measure mass loss in a reaction?

  Place the vessel on a balance
• What happens to mass during a reaction that produces gas?

  Mass decreases as gas escapes
• What is an advantage of measuring mass loss?

  It is very accurate
• What is a disadvantage of measuring mass loss?

  Gas may escape quickly
• How do you measure the volume of gas produced?

  Use a gas syringe
• What is an advantage of measuring gas volume?

  It provides precise volume readings
• What is a disadvantage of measuring gas volume?

  Not suitable for slow reactions
• How does the disappearing cross method work?

  Time how long until the cross disappears
• What is an advantage of the disappearing cross method?

  It is simple to perform
• What is a disadvantage of the disappearing cross method?

  It is subjective
• What factors affect the rate of reaction?

  1. Temperature
  2. Concentration (or Pressure in Gases)
  3. Surface Area (For Solids)
  4. Use of a Catalyst
• How does temperature affect the rate of reaction?

  Higher temperature leads to faster reactions
• How does concentration affect the rate of reaction?

  Higher concentration leads to faster reactions
• How does surface area affect the rate of reaction?

  Smaller particle size leads to faster reactions
• What is the role of a catalyst in a reaction?

  A catalyst lowers activation energy
• What is activation energy?

  The minimum energy needed for a reaction
• What increases successful collisions in a reaction?

  More frequent collisions and higher energy
• What is a catalyst?

  • Speeds up a reaction
  • Not used up in the reaction
  • Provides a different pathway with lower activation energy
• What are the advantages of using catalysts?

  Speeds up reactions and reduces energy costs
• What are the disadvantages of using catalysts?

  Can be expensive and toxic to the environment
• How to interpret reaction rate graphs?

  • Steeper slope = faster reaction
  • Levels off when reaction stops
  • Higher temperature/concentration = steeper curve
• What does a steeper slope on a rate graph indicate?

  Faster reaction
• What happens to the graph when the reaction stops?

  It levels off when reactants are used up
• How does higher concentration affect the reaction graph?

  It results in a steeper curve
• What is the required practical for measuring rate of reaction?

  • Investigate how concentration affects reaction rate
  • Use sodium thiosulfate and hydrochloric acid
  • Measure time for cross to disappear
• What is the expected result when concentration increases in the practical?

  Faster reaction, cross disappears quicker
• What are the effects of different factors on reaction rates?

  • Temperature: Higher temp = faster collisions
  • Concentration: More particles = more collisions
  • Surface Area: Smaller particles = more collisions
  • Catalyst: Lowers activation energy = faster reaction