Transcript Kinetics and the Virtual Molecular Dynamics Lab

Kinetics and the Virtual
Molecular Dynamics Lab
Kinetics Made Easy
Susan Grillo
Jay Chandler
Dan Burton
Introduction
This is a traditional kinetic unit which
incorporates Simulabs as a supplement.
Incorporation of SimuLab will aid the
visual interpretation of the kinetics of a
reaction.
Intended Audience
Advanced Placement or Chem II
Students.
The topics of kinetics and rate laws are
incorporated in the SAT II to a very
slight degree, and to a larger degree on
the AP Chem Exam.
The Simulabs are intended to enhance
the students understanding of kinetics.
Placement in the Curriculum
The unit will enhance the curriculum
already in place.
The major revision is the use of the
appropriate SimuLabs to enhance the
understanding of 1st and 2nd order
reactions and activation energy.
Students need an understanding of
reactions rates prior to starting this unit.
Adjustments / Adaptation
Honors 1
Chemistry
No Zero Order or
fractional reaction
rates.
Substitute the
Methyl Violet Lab
with the Vitamin C
Clock Lab.
Chemistry
No Graphing.
Only use Vitamin C
Clock Lab.
Only show the
relationship between
initial conc., temp.,
and rate.
Goals and Objectives
Students will define the key terms involved in
chemical kinetics and factors affecting rate.
Students will use lab data and construct graphs to
determine reaction order and the rate law.
Students will apply the Arrhenius Equation to
calculate activation energy and constants.
Students will be able to develop a procedure to
determine the rate law of a reaction.
Given experimental data, students will be able to
derive a rate law and select an appropriate
mechanism for a reaction.
Time
Instructional
•Five days are required
for instruction related to
zero, first, and second
order reactions and to
discuss the differential
and integrated rate laws,
half-life and slope
equation.
Pre-Lab, Lab and
Post-Lab
• Two days
are needed for a wet lab .
• Two days are required
for Simulabs 2.1; 2.2; 2.3.
• One day is required for
Poster/PowerPoint
presentation.
Resources
Crystal violet lab:
Crystal violet (2.0 x 10 –5 M)
NaOH (0.10M)
Set-up time is approximately 1 hour.
Demonstrations
Surface area demonstration.
Elephant’s toothpaste catalysis
demonstration:
30% H2O2 ( 125 mL)
KI
Dishwashing liquid
Food coloring
Electronic Equipment
CBL/ Spec 20
Notes: If CBL’s used then only one is
needed for graphing.
Simulab requires one computer
for every two to three students.
CBL Probes for colorimetry.
Instructional Activities
Chronology
Day One:
Introduction to reaction rates
Demonstrations
Days Two - Four:
Average rate versus instantaneous rate:
Method of initial rate
Types of rate laws
Use of integrated rates
Use of zero order, 1st and 2nd order rates
Graphing of integrated rate laws
Half-life
Instructional Activities
Chronology Continued
Day five:
Mechanisms/ rate-determining step/ intermediates
Collision model
Catalysis
Days six – nine:
Laboratories:
Crystal violet
SimuLab # 2.1, 2.2; 2.3 (From the Yellow book)
Day ten- eleven:
Poster/PowerPoint preparation & presentation
2.1 Simulab
Students will complete the lab and graph:
• [red] vs time
• 1/[red] vs time
• Ln [Red] versus time to determine k, half-life,
and order of reaction
ln [red] vs time
6
Ln [red]
5
4
3
2
y = -0.0036x + 6.0429
1
R = 0.9987
2
0
0
200
400
600
time
800
1000
1200
Simulab 2.2:
Students will complete Simulab 2.2 and
will graph:
Students will complete the lab and graph:
•
•
•
[red] vs time
1/[red] vs time
Ln [red] versus time
to determine k, half-life, and order of reaction.
Simulab 2.3:
Students will:
run Simulab 2.3 three
times at different temperatures.
calculate k for each temperature.
use the Arrhenius equation to calculate
the activation energy.
Assessment
Students must produce a traditional
lab report in response to the wet lab.
Students will submit problem sets to
be graded.
A traditional end of unit, criterionbased test will be administered.
Assessment Continued
Students will produce a PowerPoint
/Posterboard summary of their Simulab
work and answer the following questions:
1. How is the rate constant determined graphically?
2. How is the rate order determined graphically?
3. How does the initial concentration affect the halflife?
4. How does the change in temperature affect the rate
constant?
5. Using collision theory, explain the difference
between first and second order reactions.
Rate Law Summary
By integrating Simulabs with wet labs:
Students will be exposed to visual
representations of the rate laws of
various order.
Students will make connections
between the dynamic molecular models
and the graphs and equations which define
the various rate laws.
Rate Law Summary
Continued
Students will explore the relationships
between temperature, reaction rates,
and constants as well as initial
concentration and half-life.
Students will be able to calculate the
activation energy from their data.