lab 11: light and colors building and confirming tools for inquiry
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Lab 11: Light and Colors
Lab 11: Light and Colors
Building and confirming tools for inquiry
Building and confirming tools for inquiry
What is ‘color’What is ‘color’
Is there a difference between your shirt and a neon light?
Is there a difference between your shirt and a neon light?
Think With Me…Think With Me…• Why do you see (different) colors when chemicals are flamed?
• Assertion I – unlike planets, electrons are only allowed discrete energies
• Assertion II – energies that don’t take electrons to an “allowed” place are ignored
• Why do you see (different) colors when chemicals are flamed?
• Assertion I – unlike planets, electrons are only allowed discrete energies
• Assertion II – energies that don’t take electrons to an “allowed” place are ignored
Hydrogen Atom SimulatorHydrogen Atom Simulator
•http://chemsite.lsrhs.net/FlashMedia/html/flashEMR.htm
•Also in Further Explorations
•Predict what happens to an arbitrary energy photon
•Predict what happens to one that matches a difference between current and potential orbital
•http://chemsite.lsrhs.net/FlashMedia/html/flashEMR.htm
•Also in Further Explorations
•Predict what happens to an arbitrary energy photon
•Predict what happens to one that matches a difference between current and potential orbital
Types of evidence/arguments• Empirical--you saw it, touched it, etc.
• Reasoned argument from documented/identified assumptions & previous knowledge
• Repeatedly established by others
• Never: Assertions by authority regardless of the nature (or volume) of that authority
How are these different?• Using a thermometer to test temperature
• Pointing a stick, say magic words, wait for rain
• Using pH paper to count protons
• Using Ba(OH)2 ‘test’ for CO2
• Counting ‘geigs’ with a Geiger counter
• Believing in ‘global climate change’
A black box?A black box?Or a tool?Or a tool?
The Parts
Set for infinite absorbance
(blocked path)
Set wavelength
Set zero absorbance
Tool usingTool using• We have chalk at each station
• Place these in the specs (IN THE TUBE!)
• Look at the beam inside!
• Slowly (and carefully) move the wavelength selector
• What do you see?
• Reset spec to ‘correct’ wavelength
• We have chalk at each station
• Place these in the specs (IN THE TUBE!)
• Look at the beam inside!
• Slowly (and carefully) move the wavelength selector
• What do you see?
• Reset spec to ‘correct’ wavelength
Calibrating the tool (Pg. D-2)Calibrating the tool (Pg. D-2)
•***Take out test tube containing chalk***
•1) Set to CORRECT wavelength – did I mention the CORRECT wavelength?
•***Take out test tube containing chalk***
•1) Set to CORRECT wavelength – did I mention the CORRECT wavelength?
The PartsThe Parts
1.) Set CORRECT wavelength
Calibrating the tool (Pg. D-2)Calibrating the tool (Pg. D-2)
•***Take out test tube containing chalk***•1) Set to CORRECT wavelength – did I say CORRECT?
•2) Use ON/OFF knob to set needle to infinite absorbance
•***Take out test tube containing chalk***•1) Set to CORRECT wavelength – did I say CORRECT?
•2) Use ON/OFF knob to set needle to infinite absorbance
The PartsThe Parts
2) Set for infinite absorbance
(blocked path)
Calibrating the tool (Pg. D-2)Calibrating the tool (Pg. D-2)
•***Take out test tube containing chalk***•1) Set to CORRECT wavelength – did I say CORRECT?
•2) Use ON/OFF knob to set needle to infinite absorbance
•3) Clean BLANK tube and place in sample chamber. Close the lid.
•4) Use “zero” adjustment knob to set needle to ZERO ABSORBANCE
•***Take out test tube containing chalk***•1) Set to CORRECT wavelength – did I say CORRECT?
•2) Use ON/OFF knob to set needle to infinite absorbance
•3) Clean BLANK tube and place in sample chamber. Close the lid.
•4) Use “zero” adjustment knob to set needle to ZERO ABSORBANCE
The PartsThe Parts
Set zero absorbance
The PartsThe Parts
Set for infinite absorbance
(blocked path)
Set wavelength
Set zero absorbance
Calibrating your eye
• Graph paper page I-9
• Predict: how will a blue liquid absorb? A green one?
Do it• Tubes in the rack
• Find the absorbance of each color at EACH wavelength
• MOVE to the next STATION = wavelength (DO NOT ALTER THE WAVELENGTH)
•Do you trust the other groups?•RE-CALIBRATE @ each station
Do it• Tubes in the rack
• Find the absorbance of each color at EACH wavelength
• MOVE to the next STATION = wavelength (DO NOT ALTER THE WAVELENGTH)
•Do you trust the other groups?•RE-CALIBRATE @ each station
Before you start, what should
you do with your data?
Data
350 430 500 590 630 660
Violet
Blue
Green
Yellow
Red
Page I-1 in lab manual
ABSORBANCES
Do it• Tubes in the rack
• Find the absorbance of each color at EACH wavelength
• MOVE to the next STATION (wavelength)
•Do you trust the other groups?•RE-CALIBRATE @ each station
Some Dye Structures
Crystal Violet
Yellow Napthol Green
FDC Blue1
FDC Red 3
FDC Yellow5
Moving On
Remember ‘density’?
• What would you have to do to make a dye so that there were half as many collisions between dye molecules and the beam of light?
• Pick a stock solution: build a solution with ¼ absorbance of the stock.
• Confirm
• Is it consistent with all wavelengths?
PhotosynthesisPhotosynthesis
6CO2 + 6H2O + light energy C6H12O6
+ 6O2 6CO2 + 6H2O + light energy C6H12O6
+ 6O2
Photosynthesis: Intro
Photosynthesis: Intro
What’s in a leaf• Predict: what will we find when we grind up a leaf?
• Protocol: p. 11-3
• Graph absorption of spinach extract
• ‘ultra’-violet light it (high or low energy)?
• Note!! These wavelengths re-do your DNA!!
Flight of the electro
n
Fashioning an Assay• How can you tell if photosynthesis is
happening?
• What are the inputs? The products?
• How can you test for these?
• Protocol on 11-5; Exercise 4 (bullet points) –READ THOROUGHLY
• More information on 12-2
Fashioning an Assay• Do you need a control?
Fashioning an Assay1) Extract oxygen from leaves
2)Place deflated leaves in small beaker with buffer
3) Place beaker under lights
4) Control goes where?
Next week!• You’ll take the data you
have from this week to create a red-passing, blue-passing or green-passing solution
• This will be used to test whether different portions of the visible spectrum are equally potent for photosynthesis
Sadava, Life, Fig. 8-6
Pg. 11-9 and 11-10Due in lab
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