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Concentration And Spectroscopy Lab Report

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Blake Barrett

Section 01

Mr. Wang

14 September 2016

Lab Report 1

Procedure:

No changes were made; procedure was followed as written.

Results:

Table 1: Stock Dye Solution Data

Dye Solution

Peak (max) Wavelength

Absorbance

Red

516.7 nm

.930

Blue

628.5 nm

.865

Yellow

420.4 nm

.830

Table 2: Beer’s Law Data Table

Concentration

Wavelength from Table 1

Absorbance

0.1

520.0 nm

.093

0.2

518.3 nm

.201

0.4

518.3 nm

.422

0.5

518.3 nm

.517

Best-fit line equation

y=1.069x-0.0125

Table 3: Concentration of Extracted Dye

Primary color

Wavelength from

Table 1

Absorbance

Concentration (c)

Red

501.6 nm

0.143

0.145

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Calculations:

0.143 = 1.069c - 0.0125 -> 0.1555 = 1.069x -> 0.145 = c

Discussion:

1. Did your solutions in Part I obey Beer’s law? How do you know?

Yes, the solutions in Part 1 did obey Beer’s law. I know this because Beer’s law

states that there is a linear relationship between concentration and absorption,

that is, when concentration increases, so does the amount of light that the

solution absorbs. For part 1 of the experiment as the concentration increased

from 0.1 to 0.5, the absorption increased from 0.093 to 0.517.

2. Compare and contrast the features of a primary color spectrum with those of a

secondary color spectrum.

The secondary color spectrum represents colors or wavelengths opposite of

those on the primary color spectrum. For example, orange which appears at a

wavelength between 600 - 640 nm, is the opposing color to the primary color

blue which is visible at a wavelength between 450 - 480 nm.

3. Without using a spectrometer or any other instrument, how could you estimate

the concentration of an unknown dye solution?

To estimate the concentration of an unknown dye solution one could use a color

wheel similar to the one on the first page of the lab sheet.

Image: http://sustainable-nano.com/2015/07/07/fruit-colors/

4. Would you be able to use your Beer’s Law equation to calculate an unknown

concentration of another primary color? Justify your answer.

It is possible to use Beer’s law equation to calculate an unknown concentration of

another primary color, so long as absorbance (A), absorptivity (e), and length of the

cuvette (L) are known.

Reflection:

The lab was an effective, hands-on method of observing the effect of changing the

concentration of a solution on the transmission of light. It may better serve future

scientists performing this experiment to include more images of the correct - and in

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Blake Barrett Section 01 Mr. Wang 14 September 2016 Lab Report 1 Procedure: No changes were made; procedure was followed as written. Results: Table 1: Stock Dye Solution Data Dye Solution Peak (max) Wavelength Absorbance Red 516.7 nm .930 Blue 628.5 nm .865 Yellow 420.4 nm .830 Table 2: Beer’s Law Data Table Concentration Wavelength from Table 1 Absorbance 0.1 520.0 nm .093 0.2 518.3 nm .201 0.4 518.3 nm .422 0.5 518.3 nm .517 Best-fit line equation y=1.069x-0.0125 Table 3: Concentration of Extracted Dye Primary color Wavelength Table 1 Red 501.6 nm from Absorbance 0.143 Concentration (c) 0.145 Calculations: 0.143 = 1.069c - 0.0125 -> 0.1555 = 1.069x -> 0.145 = c Discussion: 1. Did your solutions in Part I obey Beer’s law? How do you know? Yes, the solutions in Part 1 did obey Beer’s law. I know this because Beer’s law states that there is a l ...
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Tags: concentration SPECTROSCOPY Beers Law equation molar extinction coefficient BeerLambert Law