rate of reaction

• What does a rate of reaction graph show on the y-axis?

  Amount of product formed or amount of reactant used up
• What does a rate of reaction graph show on the x-axis?

  Time
• How do you calculate the mean rate of reaction from a graph?

  By dividing the overall change in y-value by the total time taken
• How would you find the mean rate of reaction between two points in time on a graph?


  Calculate the change in y and divide by the change in x
• What is the mean rate of reaction between 20 s and 40 s if the volume of gas changes from 15 cm³ to 19 cm³?

  0.2 cm³/s
• What is the purpose of drawing a tangent on a reaction rate graph?

  To find the gradient at a particular point in time
• How do you calculate the gradient of a tangent on a graph?

  By using the formula: gradient = change in y ÷ change in x
• What is the rate of reaction at 3 minutes if the change in y is from 1.4 to 2.2 and the change in x is from 2.0 to 5.0?

  0.27 g/min
• What are the steps to measure the rate of reaction using magnesium and hydrochloric acid?

  1. Add dilute hydrochloric acid to a conical flask.
  2. Add magnesium ribbon and attach a gas syringe.
  3. Start the stopwatch and record gas volume at intervals.
  4. Plot a graph of time vs. volume of gas produced.
  5. Repeat with different acid concentrations.
• What is the effect of increasing acid concentration on the rate of reaction with magnesium?

  • Higher concentration leads to a faster rate of reaction.
  • More acid particles increase collision frequency.
• How can you measure the rate of reaction between sodium thiosulfate and hydrochloric acid?

  1. Add sodium thiosulfate to a conical flask on a marked paper.
  2. Add hydrochloric acid and start the stopwatch.
  3. Time how long it takes for the cross to disappear.
  4. Repeat with different concentrations of HCl.
• What is the relationship between the concentration of HCl and the time taken for the mark to disappear in the sodium thiosulfate experiment?

  Higher concentration results in less time for the mark to disappear
• What are the three methods to measure the rate of a reaction?

  Precipitation and colour change, change in mass, volume of gas given off
• How is the rate of reaction calculated?

  Rate of Reaction = Amount of reactant used or product formed / Time
• What units are commonly used to express the rate of reaction?

  cm³/s, g/s, or mol/s
• What are the factors that affect the rate of a reaction?

  1. Temperature
  2. Concentration of a solution or pressure of gas
  3. Surface area
  4. Presence of a catalyst
• How does increasing temperature affect the rate of reaction?

  It increases the speed of particles, leading to more frequent collisions
• How does increasing concentration or pressure affect the rate of reaction?

  It increases the frequency of collisions between reactant particles
• How does increasing surface area affect the rate of reaction?

  It allows more area for collisions to occur, increasing the reaction rate
• What is a catalyst and how does it affect the rate of reaction?

  A catalyst speeds up a reaction without being used up by lowering activation energy
• What is activation energy?

  The minimum energy required for particles to react
• How does collision theory explain the rate of reaction?

  The rate depends on collision frequency and energy during collisions
• How does doubling the frequency of collisions affect the rate of reaction?

  It doubles the rate of reaction
• What happens to the steepness of a reaction rate graph over time?

  The line becomes less steep as reactants are used up
• What do the slopes of reaction rate graphs indicate?

  • Steeper slopes indicate faster rates of reaction.
  • Flatter slopes indicate slower rates as reactants are consumed.
• What is the relationship between the amount of product formed and the time taken in a reaction?

  More product formed in less time indicates a faster reaction
• How can you tell if a reaction is faster based on a graph?

  By observing the steepness of the line on the graph
• What does a flat line on a reaction rate graph indicate?

  It indicates that the reaction has stopped or reached completion
• What is the effect of increasing the concentration of reactants on the rate of reaction?

  It increases the rate of reaction
• Why is it important to keep certain variables constant in an experiment?

  To ensure a fair test and valid results
• What should be done if a reaction is too vigorous when using a gas syringe?

  Be careful to avoid blowing the plunger out of the syringe
• What is the significance of measuring the rate of reaction in the chemical industry?

  Faster reactions lead to increased production and profit
• How does the presence of a catalyst affect the activation energy of a reaction?

  A catalyst lowers the activation energy required for the reaction
• What is the role of temperature in collision theory?

  Higher temperatures increase particle speed and collision energy
• What happens to the rate of reaction as the surface area of a solid reactant increases?

  The rate of reaction increases
• How does the concentration of a solution affect the number of collisions in a reaction?

  Higher concentration increases the number of particles, leading to more collisions
• What is the relationship between the rate of reaction and the energy of collisions?

  Higher energy collisions increase the likelihood of a successful reaction
• Why is it important to understand collision theory in relation to reaction rates?

  It helps explain how different factors affect the rate of reaction
• What is the effect of a catalyst on the overall reaction equation?

  A catalyst is not part of the overall reaction equation
• How does the reaction rate change as reactants are consumed over time?

  The reaction rate decreases as reactants are used up