DATA TABLES A. POWDERED DRINK SOLUTION 611m933 Mass of beaker Mass of beaker+ po

ID: 1052374 • Letter: D

Question

DATA TABLES A. POWDERED DRINK SOLUTION 611m933 Mass of beaker Mass of beaker+ powdered drink Mass of powdered drink (show calculation) 0.3tI9 62.12123-6 L73 g-0.3119g B. PREPARATION OF STANDARD SOLUTIONS. Molarity of stock solution (from label) Calculate the molarities of your standard solutions and record in the data table below. STANDARD SOLUTION MIXTURES 5.00x 10 M Solution number Volume of stock solution (mL) 2.00 4.00 6.00 8.00 10.00 Molarity of standard solution (M) 4 6.00 x106M 5 Calculations 5o0xo M2.oomL 0.0OnL 500th ard so on 10 I SPECTROPHOTOMETRIC ANALYSIS OF BLUE DYE REPORT FORM

Explanation / Answer

C) Prepare the table as below for plotting Beer’s law:

Solution

Molarity (M)

Absorbance

Blank

0.00

2.00*10-6

0.14

4.00*10-6

0.35

6.00*10-6

0.56

8.00*10-6

0.76

10.00*10-6

0.97

Powdered drink

0.64

Plot the graph.

From the plot above, we can easily find the following values:

Slope = 98857 M-1 (ans).

The unit is obtained by remembering that absorbance A = .c.l where A is the absorbance (dimensionless), c is the molar concentration (M) and l is the path length (cm). Therefore, the unit for the molar absorptivity is M-1cm-1. The slope of the plot is .l and the unit of the slope is M-1.

Intercept = -0.031

Line equation: y = 98857x – 0.031

D) Directly from the graph:

I believe this means that we need to use Beer’s law directly.

Put .l = 98857 M-1 and A = 0.64

Therefore,

0.64 = (98857 M-1)*c

====> c = 6.47*10-6

The molarity of the blue dye in the powdered drink = 6.47*10-6 M = 6.47*10-6 mol/L (ans).

Mass of blue dye in the solution:

To calculate this part and the subsequent part, I need to know how the sample of the blue dye was prepared. In particular, what was the volume of the solution in which the blue dye was dissolved and the molar mass of the blue dye.

Percent blue dye in the powdered drink:

Need the same information as above.

From the equation of the line:

Put y = 0.64 in the equation of the line and obtain

0.64 = 98857x – 0.031

====> 98857x = 0.671

====> x = 6.79*10-6

The molarity of the blue due calculated from the equation of the line is 6.79*10-6 M.