A spectrophotometer was used to determine the absorbance of 2 pigments between 400 nm and 710 nm, the range of wavelengths that is associated with visible light. The table below contains the absorbance values for each pigment (“Pigment 1” and “Pigment 2”) at wavelengths separated by approximately 10 nm. Wavelength Pigment 1 Pigment 2 400 0.097 0.117 410 0.088 0.127 420 0.099 0.143 430 0.113 0.158 440 0.129 0.181 450 0.158 0.184 460 0.145 0.171 470 0.085 0.164 480 0.041 0.143 490 0.024 0.089 500 0.022 0.048 510 0.019 0.023 520 0.018 0.014 530 0.020 0.010 540 0.019 0.008 550 0.020 0.008 560 0.022 0.009 570 0.023 0.008 580 0.025 0.008 590 0.028 0.006 600 0.029 0.008 610 0.028 0.009 620 0.028 0.010 630 0.035 0.010 640 0.061 0.008 650 0.068 0.008 660 0.051 0.009 670 0.032 0.008 680 0.015 0.007 690 0.010 0.006 700 0.009 0.006 710 0.007 0.006 Table 1. Absorbance of two different pigments at wavelengths between 40 nanometers (nm) and 710 nm. Graph the absorption spectrum for each pigment. You can use Excel, Google Sheets, or graph the data by hand. If you graph it by hand, you must still scale your X and Y axis so that all the data appears on one page. Graph paper is fine to use. The data from both pigments should be plotted on the same graph. You will be including this graph in your lab writing assignment this week, so if you are confused about this process, be sure to seek clarification early in the week. After you have generated your data, answer the following questions. What is the independent variable in this experiment? What is the dependent variable in this experiment? Based on your graph, what is the identity of pigment 1? Based on your graph, what is the identity of pigment 2?
Chemistry of Life
The field in which the chemical properties, structure, location, and biological processes in the body are studied is the chemistry of life. The term chemistry of life incorporates chemistry in the life processes; the study of life processes comes under biology.
Covalent and Ionic Bonds
Atoms of different elements except noble gases do not have a complete octet, so they combine with other atoms to form a chemical bond. When two atoms of the same and different elements mutually share two electrons, one by one, to form a bond between them, the bond is called a covalent bond. On the other hand, an electrovalent or ionic bond is formed when a metal atom transfers one or more electrons to a non-metal atom.
Carbon Bonding
It is basically an association between two C that is formed by sharing a pair of electrons among them. Commonly, this is a single or sigma (σ) bond. Sometimes double or triple or pi (Π) bonds can also be formed. These are formed when orbitals of two C atoms get hybridized.
Alcohols, Phenols and Ethers
Alcohols are hydroxyl (-OH) group or moiety containing organic aliphatic molecule. They are produced when a hydrogen atom of an aliphatic compound is substituted with hydroxyl moiety. The general expression of alcohol is R-OH, where the R is an aliphatic group. Their general formula is CnH2n+2O, where n = number of carbon atoms. If n = 1, then CH4O = CH3OH or methanol, n = 2, C2H6O = C2H5OH ethanol.
Exercise C: Spectrophotometry
Watch this video to learn how a spectrophotometer works. For additional information, you can read about using a spectrophotometer in your textbook’s “BioSkills 8: Using Spectrophotometry”.
A spectrophotometer was used to determine the absorbance of 2 pigments between 400 nm and 710 nm, the range of wavelengths that is associated with visible light. The table below contains the absorbance values for each pigment (“Pigment 1” and “Pigment 2”) at wavelengths separated by approximately 10 nm.
|
Wavelength |
Pigment 1 |
Pigment 2 |
|
400 |
0.097 |
0.117 |
|
410 |
0.088 |
0.127 |
|
420 |
0.099 |
0.143 |
|
430 |
0.113 |
0.158 |
|
440 |
0.129 |
0.181 |
|
450 |
0.158 |
0.184 |
|
460 |
0.145 |
0.171 |
|
470 |
0.085 |
0.164 |
|
480 |
0.041 |
0.143 |
|
490 |
0.024 |
0.089 |
|
500 |
0.022 |
0.048 |
|
510 |
0.019 |
0.023 |
|
520 |
0.018 |
0.014 |
|
530 |
0.020 |
0.010 |
|
540 |
0.019 |
0.008 |
|
550 |
0.020 |
0.008 |
|
560 |
0.022 |
0.009 |
|
570 |
0.023 |
0.008 |
|
580 |
0.025 |
0.008 |
|
590 |
0.028 |
0.006 |
|
600 |
0.029 |
0.008 |
|
610 |
0.028 |
0.009 |
|
620 |
0.028 |
0.010 |
|
630 |
0.035 |
0.010 |
|
640 |
0.061 |
0.008 |
|
650 |
0.068 |
0.008 |
|
660 |
0.051 |
0.009 |
|
670 |
0.032 |
0.008 |
|
680 |
0.015 |
0.007 |
|
690 |
0.010 |
0.006 |
|
700 |
0.009 |
0.006 |
|
710 |
0.007 |
0.006 |
Table 1. Absorbance of two different pigments at wavelengths between 40 nanometers (nm) and 710 nm.
Graph the absorption spectrum for each pigment. You can use Excel, Google Sheets, or graph the data by hand. If you graph it by hand, you must still scale your X and Y axis so that all the data appears on one page. Graph paper is fine to use. The data from both pigments should be plotted on the same graph. You will be including this graph in your lab writing assignment this week, so if you are confused about this process, be sure to seek clarification early in the week.
After you have generated your data, answer the following questions.
- What is the independent variable in this experiment?
- What is the dependent variable in this experiment?
- Based on your graph, what is the identity of pigment 1?
- Based on your graph, what is the identity of pigment 2?
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