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Sit with last week’s group

Sit with last week’s group. Turn in… Dilutions worksheet

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Page 1: Sit with last week’s group. Turn in… Dilutions worksheet

Sit with last week’s group

Page 2: Sit with last week’s group. Turn in… Dilutions worksheet

Turn in…

• Dilutions worksheet

Page 3: Sit with last week’s group. Turn in… Dilutions worksheet

Goals

• Consider implications of plants being ‘green’

• Use O2 creation as a measurement of photosynthesis

• Test a common claim from textbooks

Page 4: Sit with last week’s group. Turn in… Dilutions worksheet

Here’s an assertion…

Can we test this?

Photosynthesis in (green plants) is more effective at the ends of the spectrum than in the middle

Page 5: Sit with last week’s group. Turn in… Dilutions worksheet

HOW can we test it

• What did we do with leaves last week?– Leaf assay– Graph of absorption spectrum

• How did that happen?

• How can you make your data meaningful?

• How might we subject leaves ONLY to certain wavelengths?

Page 6: Sit with last week’s group. Turn in… Dilutions worksheet

• Groups 1 & 2: liquid permitting red light

• Groups 3 & 4: liquid permitting green light

• Groups 5 & 6: liquid permitting blue light

• All: make enough to share (yours + 2 others)

• Final exp. 20 mLs, so how much to make?

Getting Started

Page 7: Sit with last week’s group. Turn in… Dilutions worksheet

What will it look like?• Need to place disks in at same time?

• What do you time?

• Does concentration matter?

• How can you make comparisons valid?

Page 8: Sit with last week’s group. Turn in… Dilutions worksheet

Consider…

• What is the mechanism by which we are ‘removing’ some wavelengths of light?

• Implications for volumes of beakers?

• Consequences if red sits waiting while you work with blue and green

• Again, when should we start extracting O2?

Page 9: Sit with last week’s group. Turn in… Dilutions worksheet

Buffers• Ca++ and PO4-- precipitate

• So, TWO different 10X buffer components

• Add ONE of the them last or get a solid

Page 10: Sit with last week’s group. Turn in… Dilutions worksheet

A tool for making dyes:Plotulence

Page 11: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

Page 12: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

Absorbance values

Page 13: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

Concentration (_X)Absorbance values

Page 14: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

Concentration (_X)Absorbance values

Resulting mixture

Page 15: Sit with last week’s group. Turn in… Dilutions worksheet

Your Goal• Let in as much light as possible for your

‘region’ of the spectrum– Red: include both 630 & 660– Blue: 350 & 430– Green: 500 & 590

• Given the above, block as much as possible at other wavelengths

• Absorbance no more than .2 at your wavelengths and no greater than 2 at other waves

Page 16: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

• Use ‘Plotulence’ to develop your dye cocktail

• Again, sliders indicate how much more concentrated than last week

• Check with other group of same color

• We’re not making artificial hearts or sending a probe to Mars

Page 17: Sit with last week’s group. Turn in… Dilutions worksheet

Open Plotulence

• On desktop

Page 18: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence• ‘Start Table’• Enter your data• Use sliders

Red = 630 and 660Blue = 350 and 430Green = 500 and 590

Absorbance no more than 0.2 at your wavelength and no greater than 2 at other wavelengths!!!!

Page 19: Sit with last week’s group. Turn in… Dilutions worksheet

Plotulence

Concentration ( e.g., 1.35X )Absorbance values

Resulting mixture absorbances

mixture

Page 20: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

Page 21: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

Page 22: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?

Page 23: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

Page 24: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?

Page 25: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?– Yes, we have that, too! – slider values

Page 26: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?– Yes, we have that, too! – slider values

• What are we missing?

Page 27: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?– Yes, we have that, too! – slider values

• What are we missing?– Indv. dye volumes

Page 28: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?– Yes, we have that, too! – slider values

• What are we missing?– Indv. dye volumes

• What makes up the rest?

Page 29: Sit with last week’s group. Turn in… Dilutions worksheet

What do we have?• Starting concentration of dyes/buffers?

– 10X

• Final volume?– 100 mLs (how much of it is buffer?)

• Desired dye concentrations?– Yes, we have that, too! – slider values

• What are we missing?– Indv. dye volumes

• What makes up the rest?– Distilled water

Page 30: Sit with last week’s group. Turn in… Dilutions worksheet

Mix It• Remember there are TWO ‘buffers’

– Do not place at same time – ONE goes last

• Compare your plan to other group’s• Mix your color• Trade ‘colors’ with your friends; collect all

three!!!!• Get your disks• Float ‘em• Controls?

Page 31: Sit with last week’s group. Turn in… Dilutions worksheet

What if one ‘color’ is darker?• What can we do to account for differences in

the AMOUNT of light allowed through the solution? HOW?

Page 32: Sit with last week’s group. Turn in… Dilutions worksheet

What if one ‘color’ is darker?• Test your color using specs• Graph (from lab manual) your data using

smoothed curves• Cut out the graph ABOVE line• Weigh it; record it; compare it• What does that number represent?• Y-axis:4th major line from bottom as 2.0 abs• X-axis: each major line is 100nm; plot 300-700

nm• Give your graph weight to ‘sharing’ groups!

Page 33: Sit with last week’s group. Turn in… Dilutions worksheet

What Now?

• Did you find what you expected?

• Stones left unturned?

• Differences in graph weights?– Red, graph 3g, floated in 5 min– Blue, graph 2g, floated in 7 min

• Adjusted time?

This is a critical part of your experiment. Failure to explain and deliver this calculation = loss of points on write up

Page 34: Sit with last week’s group. Turn in… Dilutions worksheet