Calculating Relative Rate in Chemistry

Introduction

• Focus on calculating relative rate.
• Assumption: Familiarity with calculating average rate from previous learning.
• Average Rate Formula: Change in quantity divided by change in time.

Importance of Relative Rate

• Used when a measurable quantity isn't available, e.g., color change in reactions.
• Equation for relative rate found on page 4 of the data book.
• Rates usually measured in seconds, expressed as per second.

Calculations

• Relative Rate Formula: Rate = 1 / Time
  • Example: 58 seconds → Relative Rate = 0.017 per second.
• Rearranging for Time: Time = 1 / Rate
  • Example: Rate = 0.2 per second → Time = 5 seconds.

Practical Example

• Reaction: Acidified potassium permanganate and oxalic acid.
  • Notable color change: Deep purple to colorless.
  • Performed between 40-70 degrees for optimal observation.
• Calculating rate for this reaction:
  • Rates at different times: 0.011, 0.025, 0.059, 0.120 per second.
  • Observes correlation between temperature rise and rate increase.

Graphical Analysis

• Plotting temperature vs. rate shows a non-linear relationship (curve).
• Example Problem: Determine reaction time at 55 degrees using extrapolation.
  • Rate found to be 0.04 per second.
  • Time calculation: 1 / 0.04 = 25 seconds.

Conclusion

• Discussion on the first topic of higher chemistry: controlling the rate.
• Encouragement to watch more educational content and social media engagement.

Note: These notes are meant to serve as a study aid and reference for understanding the concept of calculating relative rate in chemistry.