Lab 9- determing the concentration of dyes

What is the lamda max for Tartazine yellow?

427nm

What is the lamda max for Coomassie Blue?

576.1 nm

What chemicals and glassware is needed for this experiment?

• Unknown assigned dye stock solution

• DI water

• Cuvette for the spectrometer

• Volumetric flask 10mL

• 50mL beaker

• 5mL pipet

• graduated cylinder

• waste beaker

How do you prepare your solution?

• record the unknown dye solution given and write down its lamda max

• Measure out about about 35 mL of the dye stock solution (put the solution into a beaker then transfer to appropriate glassware)

• Poor the solution into the 50mL beaker labeled stock solution

• Rinse the volumetric flask and pipet with DI water 2 rinses

• Put a cuvette filled water into the spectrometer (triangle facing the path of light) and hit the O ABS 100%T button

• Then put a cuvette with the concentrated solution in and measure the absorbance

• Put 0.2mL of the concentrated solution into a volumetric flask

• Fill the rest of the flask with DI water (meniscus should be at the calibration mark)

• Swirl gently to mix the dye with the water.

• Put the diluted solution into the spectromter and record the absorbance

what are the variables in beers law equation? 

y= absorbance (A)

x- concentration (M) 

What is the dilution factor formula?

DF= Vfinal / Vinitial

How to calculate the original concentration?

Orig Conc= Conc of diluted sol * DF

What should we observe from this lab?

Absorbance and Concentration are directly related

What is the Lambda max for the red dye?

509nm