Measuring rate of reaction

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

  To measure mean rate of 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?

  5 cm³ per second
• Why does the average rate of reaction not reflect actual rates?

  Because reactions slow down over time
• What does a steep curve on the graph indicate?

  A high rate of reaction
• What happens to the rate of hydrogen production as magnesium is used up?

  The rate of hydrogen production decreases
• 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 actual rate of reaction at a specific time?

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

  A line that touches the curve at one point
• How do you find the gradient of the tangent line?

  Change in y divided by change in x
• If the change in volume of hydrogen is 600 and change in time is 170 seconds, what is the rate?

  3.53 cm³ per second
• What is the significance of the tangent's length when calculating the rate?

  Longer tangents provide more accurate values
• What would a graph of magnesium remaining against time show?

  It would decline rapidly at first
• How do you find the rate of reaction at one minute using the magnesium graph?

  Draw a tangent and calculate the gradient
• If the change in magnesium is 0.72 grams and change in time is 100 seconds, what is the rate?

  0.0072 grams per second
• What should you do if your tangent is not perfect?

  Examiners allow small ranges of values
• What are the steps to calculate the mean rate of reaction from a graph?

  1. Identify the time period on the x-axis.
  2. Draw a dashed line to intersect the curve.
  3. Find the corresponding volume on the y-axis.
  4. Divide the volume by the time period.
• What are the steps to calculate the actual rate of reaction at a specific time?

  1. Identify the specific time on the x-axis.
  2. Draw a tangent to the curve at that point.
  3. Calculate the gradient of the tangent.
  4. Use the formula: gradient = change in y / change in x.
• What are the differences in the graphs of hydrogen production and magnesium remaining?

  • Hydrogen production graph: steep curve, then plateau.
  • Magnesium remaining graph: starts high, declines gradually.