This is a Chemistry problem I cannot figure out

Question

A researcher is studying the effects of bleach on blue food dye, C37H34N2O9S3Na2 (792.86 g/mol).

(a) Water is added to 0.200 g of the dye until the volume is 500. mL. What is the molarity of the solution? Show your calculation. 

(b) The chemist uses a 0.50 mL sample of the solution prepared in (a) to prepare a 100.0 mL diluted solution.  What is the concentration of the diluted solution?

The diluted solution is placed in a dry 3.0 cm cuvette, and its absorbance is measured using a spectrophotometer set to a wavelength of 412 nm. A calibration curve for this dye is shown below. Note the concentration is given in micromolar on calibration curve. (1 M = 1 x 106 µM)

 

(c) Determine the molar absorptivity of the dye.

(d) What would be the measured absorbance if the concentration of the dye was changed to 1.04 x 10-5 M?

Answer 1

a

0.200/792.86=0.000252mol

0.000252mol/0.500L=0.000505 Molar

b

dilution equation

(0.00505)0.50=M(100)

M=2053E-5

c)

A=abc

absorbance=(molar absorbtivity)path length(concentration)

c=change from micromolar to molarity

b=A/(ac)

d)

divide the 2 concentrations, like a proportion

c/A = c/A