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Kinetic Approach to Water Flow (4 Favorites)

LAB in Reaction Rate, Order of Reaction . Last updated February 22, 2018.


Summary

This lab uses the principles of chemical kinetics without using a chemical reaction. It’s an effective means to introduce the important relationship between concentration and time at an introductory level. Students will have the opportunity to analyze data and make important connections through graphing their data.

Grade Level

High school

Objectives

By the end of this lab, students should be able to

  • Properly use a burette, and collect data using it.
  • Plot the data collected in multiple ways.
  • Recognize the graphical relationships for zeroth, first, and second order kinetics.
  • Determine the value, from the most linear graphical data, for the constant, k, and the units for that constant.
  • Use Excel to analyze data collected.

Chemistry Topics

This lab supports students’ understanding of

  • Kinetics
  • Reaction Rate
  • Order of Reactions

Time

Teacher Preparation: 15 minutes

Lesson: 50 minutes

Materials

  • Water
  • Ring stand
  • Burette clamp
  • 50 mL burette
  • 50 mL beaker
  • Funnel
  • Stopwatch or other timing device
  • Access to computers with Excel or similar graphing program

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.

Teacher Notes

  • The rate of a reaction can be represented through the concentration of the reactants and time. Reactions can go fast or slow. By determining the rate order for a reaction one can go on to predict what the concentration might be in 10 or 20 seconds or 10 or 20 years. For example the Chlorofluorocarbon molecules (CFC’s) in the atmosphere that threatens to ozone layer change at a very slow rate. Or some nuclear decay may take thousands of years. Although this activity does not represent CFC’s concentrations with time or any nuclear decay, it does provide students with the tools to conduct such analysis on real data.
  • Students should be familiar with the rate order graphs prior to this lab. This video can serve as helpful background/review information “The Rate Law”, by Bozeman Science prior to class.
  • This simple activity is a good precursor to lecture notes regarding the integrated rate laws. Students collect the data, graph the data, and then draw conclusions regarding reaction orders and the integrated rate laws.
  • I find this method helps students internalize the concepts more readily than reading and lecture alone.

Variations/Additions to the lab:

  • If you have access to lap timers, the data could be collected in two continuous runs setting a lap at each interval and save time.
  • Students can collect the data through a continuous run method rather than the “refill” method as described in this lab procedure.
  • Students could graph the data on graph paper rather than using Excel to make it a more mathematical activity.
  • Extension activities:

CFC and other greenhouse gas data could be analyzed to provide a real world application using NOAA’s Annual Greenhouse Gas Index. An activity for a simpler application could link this NOAA activity to greenhouse gases.

For the Student

Background

Reactions can go fast or slow. By determining the rate order for a reaction one can go on to predict what the concentration might be in 10 or 20 seconds or 10 or 20 years. For example the Chlorofluorocarbon molecules (CFC’s) in the atmosphere that threaten the ozone layer change at a very slow rate, or some nuclear decay may take thousands of years. Although this activity does not represent CFC’s concentrations with time or any nuclear decay, it does provide for you the tools to conduct such analysis on real data.

Objective

To determine if the water flow through a vertical column is zero, first, or second order with respect to time vs. water remaining. You will work with Excel to analyze the data collected.

Materials

  • Water
  • Ring stand
  • Burette clamp
  • 50 mL burette
  • 50 ml beaker
  • Funnel
  • Stopwatch or another timing device
  • Computer with access to Excel

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow the teacher’s instructions for cleanup of materials and disposal of chemicals.

Procedure

  1. Clean and thoroughly rinse a 50 mL burette with water before beginning.
  2. Fill the burette to the 0.00 mL mark with deionized water assuring no air bubbles are in the tip.
  3. Place a 50ml beaker underneath the burette.
  4. Open the stopcock while simultaneously starting the stop watch. When the water reaches 5 mL, stop the watch and record the time required to drain 5.00 mL from the burette in the data table.
  5. Refill the burette to the 0.00 mL mark (you can reuse the water that was drained in step 4).
  6. Open the stopcock while simultaneously starting the stop watch. When the water reaches 5 mL, stop the watch and record the time required to drain 10.00 mL from the burette in the data table.
  7. Repeat step 5 and 6, by recording the times to drain 15.00mL, 20.00mL, 25.00mL, 30.00mL, and 35.00mLof water
  8. Repeat the process again so that you complete two trials for each volume.

Data

Volume Used
5.00mL 10.00mL 15.00mL 20.00mL 25.00mL 30.00mL 35.00mL
Time
(Trial #1)

Time
(Trial #2)

Average Time

Calculations

  1. Complete the necessary calculations and organize the following data in within an Excel spreadsheet:
Volume Drained, mL Remaining Volume, mL In Volume Remaining
1/ Volume remaining, mL-1 Time1, sec Time2, sec Timeaverage sec
  1. Using your data, use Excel to construct graphs of each of the following:
File
File
File
  1. Include R2 and an equation for a linear fit for each graph prepared.

Analysis

  1. Based on you results, explain whether the flow of water through a burette is zeroth, first, or second order.
  2. Determine the value of the rate constant including the appropriate units.

Extension

Look at the NOAA Annual Greenhouse Gas Index website and examine data for one of the greenhouse gases. Determine the order of the reaction, using the same method outlined in this activity.