How to Calculate the Rate of Reaction

• What is the purpose of using graphs in the video?

  To measure the mean rate of a reaction
• How is the rate of reaction calculated?

  By dividing reactants used or products formed by time
• If 1200 cm³ of hydrogen is produced in 4 minutes, what is the rate of reaction?

  240 cm³ per minute
• Why does the rate of reaction slow down over time?

  Because reactants are being used up
• What does a steep curve on the graph indicate?

  A high rate of reaction
• What are the axes labeled in the reaction graph?

  X-axis: time, Y-axis: volume of hydrogen
• How do you calculate the mean rate of reaction over three minutes?

  Divide hydrogen produced by three minutes
• How do you find the rate of reaction at a specific time?

  Calculate the gradient of the curve at that point
• What is a tangent in the context of the graph?

  A straight line that touches the curve
• What is the formula for calculating the gradient of the curve?

  Change in Y divided by change in X
• What does a gradient of 3.53 cm³/s represent?

  The rate of reaction at two minutes
• What is the initial amount of magnesium used in the reaction?

  1.2 grams
• How do you find the rate of reaction at one minute?

  Draw a tangent and calculate the gradient
• What is the change in Y when finding the rate at one minute?

  About 0.72 grams
• If the change in time is 1 minute 40 seconds, what is it in seconds?

  100 seconds
• What is the final rate of reaction calculated at one minute?

  0.0072 grams per second
• What are the two main tasks you can perform with the reaction graph?

  • Calculate the mean rate of reaction over a period
  • Calculate the actual rate at a specific time
• What should you do if your tangent is not perfect?

  Examiners allow small ranges of values
• What are the characteristics of the reaction graph over time?

  • Starts steep due to high reactant availability
  • Gradually flattens as reactants are consumed
  • Plateaus when reactants are fully used