Name: Arnold Mark Samai.
Date : 8th November 2007
Unit Title: Analytical Chemistry and Spectroscopy.
Form: Upper six.
Time : 2 hours.
Strategy: Inquiry based learning.
References:
CAPE chemistry by Mr. Arnold Mark Samai & Mrs. Susan Maraj (2007).
Internet sites to be provided in the web quest.
Prerequisites:
Knowledge: students should know
The origin of uv-vis spectroscopy
Resources to be used:
Computer, Textbooks.
Skills to be developed:
communicating, problem solving, decision making, drawing and evaluating conclusion
Materials and Resources:
For teacher and students
Computer with high speed internet access.
Concept Statement: Analytical Chemistry involve the analysis of samples in very dilute concentrations. UV Vis spectroscopy is one technique that can be used to analyze colored samples. The phosphate concentration of water can be determined using UV Vis spectroscopy.
Objectives.
At the end of the lesson, students will be able to: Classification
Explain the basic steps involved in analyzing samples by UV/VIS
spectroscopy. Application
Calculate the concentration of a given species using Beer-Lamberts law Analysis
Explain the procedure for analyzing a colorless substance by UV/VIS
spectroscopy Application
PROCESS SKILLS
During this lesson, student will be engaged in:
Designing and Planning an experimental procedure X
Recording data and observations X
Communicating scientific ideas, observations and arguments X
Applying scientific ideas and methods to solve qualitative and X
quantitative problems
Decision-making based on examination of evidence and arguments X
Activities : Set Induction
Introduction: Teacher begins class by recapping the scenario of the Maria Panday.
This case study sets analytical Chemistry within the context of a forensic investigation of a suspicious death.
On February 10th, 2007, Joy Manning found her friend Maria Panday dead in a river 100m from her home. After an initial search on the crime scene by the crime officers, the body was taken to the morgue. Door–to-door enquires revealed evidence of a boundary dispute between Maria Panday, David Dookeran and two of her children Uma Panday and Mikey Panday. Maria’s hair and clothing were completely wet, and the coroner estimated that she died within an hour of when the body was found. An autopsy revealed large quantities of water in her lungs, and the cause of death was listed as drowning.
In view of the circumstances, the police have labeled this death a homicide. Primary suspicion falls on David, Uma and Mikey. All of the adult children would inherit substantial fortunes from their mother, and all were known to have recently argued with her.
Knowing where the drowning took place will help the police to possibly narrow their list of suspects. There are only three bodies of water within a one-hour radius of where her corpse was found. They are the swimming pool at the local country club; a large stock pond on one son's ranch, and a mine-waste settling pond close to the river where she was discovered.
A chemical analysis of the water from Maria’s lungs reflected abnormally high concentrations of phosphates. It is hoped that analysis of water from the three possible drowning sites will pinpoint exactly where Maria drowned and thus provides a clue regarding his murderer.
Each group of students is investigating the suspicious death of Maria Panday. UV/VIS spectroscopy is one of the most powerful tools that can be used to analyze water samples. Your task is to explore the use of UV/VIS outlining how this case can be solved.
Development:
Teacher then asks students to work in pairs and use the web quest provided to channel a course
that can be taken to solve the death of Maria Panday.
Teacher allows groups to read the guidelines and ask questions as is customary with inquiry based learning.
The Essential Question:
The essential questions frame the research; they require Ss to make decisions and plan courses of action.
What exactly does the UV/ VIS spectrophotometer measure?
What plan can I develop to determine where Maria drowned?
Foundation questions
These are the questions. These provide a factual foundation from which the answers to the essential questions can be developed.
How did Maria Panday die?
What was present in her lungs?
Was the water in his lungs analyzed?
What were the analytes found in the water in his lungs?
Where did the phosphates in the water come from?
Was the water in the ponds analyzed?
How do we test the water in the pond?
What techniques can we use?
Were samples collected from the pond?
Did his body bore any marks of violence?
What were the contents of his will?
Developing a search Strategy
Here the students develop a search strategy for locating web information by closely examining the foundation questions for key words. Suitable searches can include:
(1) Analysis of phosphate content of the water
(2) Spectrophotometer
(3) Auxochrome – Colour development
(4) Procedure for analysis of phosphate in water
(5) Redox reactions
(6) Calibration curves
(7) Beer-lamberts Law
(8) Dilution of samples
CONSOLIDATION
1. Using a diagram explain the basic steps involved in the analysis of a sample using the UV/VIS Spectrophotometer.
2. What steps must be taken to analyze a colorless sample using UV/VIS spectroscopy.
3. Outline the procedure that must be taken to solve the case. You should write a 1000 word extended essay highlighting the procedure that should be followed.
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