Title: Up in the air
Author: Jamie Poland, University of Houston Clear Lake TES, 2005
Grade Level: 8th
TEKS:
Sample TEKS for the 8th grade:
 2a, 2b, 2c, 2d, 4a, 4b, 5a, 5b, 5c, 9d
Objectives:
The students will be able to:
1. Identify the chemical makeup of different air pollutants.
2. Calculate the atomic mass and the molecular mass of chemicals.
3. Explain the basics of chromatography
Vocabulary:
Air Pollution, Chromatography, Empirical formula, Atomic mass, Molecular mass
Materials:












Coffee filter
Black marker (non-permanent)
Glass beaker about 6 inches tall
Pencil
Tape
A 50/50 tubbing alcohol and water mixture
6 different size round objects, ranging in size from 1/8 inch to 3 inches in diameter
o Size 1 (smallest) will represent Hydrogen atoms. At least 275 pieces are needed.
o Size 2 will represent Carbon atoms. At least 170 pieces are needed.
o Size 3 will represent Oxygen atoms. At least 90 pieces are needed.
o Size 4 will represent Sulfur atoms. At least 25 pieces are needed.
o Size 5 will represent Chlorine atoms. At least 30 pieces are needed.
o Size 6 (largest) will represent Lead atoms. At least 10 pieces are needed.
10 shoebox sized plastic containers
Student scissors
10 sets of atoms. Each set will contain one of each of the sizes of atoms.
Copies of a periodic table
Copies of the “Chemical analysis of air pollutants” student worksheet for each student
Background
Chromatography is a technique used to physically separate and identify the components
within a mixture. Gas liquid chromatography (GLC) or simply gas chromatography (GC) is
more versatile, widely used, and industrially important than paper chromatography.
Chromatography is based on the principle that different molecules are adsorbed to a
different extent by different kinds of substances. This fact can be used to separate mixtures of
various substances.
When doing a paper chromatography experiment, the dyes in water soluble inks differ in
their tendency to adhere to water adsorbed onto the filter paper and are carried different
distances along the filter paper by the solvent water, and separated. The water adsorbed onto
the filter paper or chromatography paper is called the stationary phase, and the solvent which
carries the mixture to be separated is called the mobile phase.
In gas chromatography, the stationary phase is generally a non-volatile liquid, which coats
an inactive, pulverized, solid material packed within a very thin column. The mobile phase is
generally an inert gas such as helium and is referred to as a carrier gas.
The components of the mixture to be separated must be volatile (which means it readily
passes into the gas state at a relatively low temperature). A very small amount of solution is
injected into the injection port of the chromatograph using a syringe. The mixture is
immediately vaporized and carried by the carrier gas into the column. The column, as well as
the injection port and the detector are kept at a controlled temperature inside an oven so that
the mixture remains in vapor form. From the time the materials are injected into the instrument
until they reach the detector, they are being retained by the liquid in the column (the stationary
phase).
The time each substance is retained is called its retention time, and is usually represented
as minutes. Techniques are chosen so that each component of the mixture has a different
retention time and, therefore, reaches the detector separately and appears as a peak on a
chromatogram.
Teacher Setup
1. Prepare the following chemical samples using the 6 different sized “atom” pieces in 10
different containers. Label container with sample # only. Do not write the names or the
chemical formulas. These will be used by the students during their lab experiment.
Sample 1: Carbon Monoxide (CO)
Sample 6: Butadiene (C4H6)
30 Carbon, 30 Oxygen (Factor of 30)
Sample 2: Methane (CH4)
40 Hydrogen, 10 Carbon (Factor of 10)
Sample 3: Gasoline (C8H18)
54 Hydrogen, 24 Carbon (Factor of 3)
Sample 4: Lead tetraethyl Pb(C2H5)4
40 Hydrogen, 16 Carbon, 2 Lead (Factor of 2)
Sample 5: Hydrochloric Acid (HCl)
18 Hydrogen, 18 Carbon (Factor of 18)
36 Hydrogen, 24 Carbon (Factor of 4)
Sample 7: Sulfur Dioxide (SO2)
30 Oxygen, 15 Sulfur (Factor of 15)
Sample 8: Acetaldehyde (CH3CHO)
32 Hydrogen, 16 Carbon, 8 Oxygen (Factor of 8)
Sample 9: Benzene (C6H6)
24 hydrogen, 24 Carbon (Factor of 4)
Sample 10: Formaldehyde (CH2O)
24 Hydrogen, 12 Carbon, 12 Oxygen (Factor of 12)
2. Prepare a paper chromatography demonstration.
o Cut the coffee filter into a 2 inch by 6 inch wide strip.
o Measure 1.5 inches down one side and draw a line with a
pencil.
o Using the marker, put a large black dot in the center of the line.
o Tape the other end of the filter on the pencil
o Place about 1 inch of the alcohol mixture into the beaker
o When ready, you will put the pencil on top of the beaker and
submerse the part of the coffee filter below the line into the
alcohol mixture.
o **NOTE- Do not let the ink dot get submersed in the liquid
Lesson
Note: This activity should follow a study of air quality issues. Students should also
understand the basics of a chemical formula, as well as how to use an empirical formula.
Day one
1. About 10 minutes before you start the lesson off, start the paper chromatography
demonstration.
2. Hold up the black marker used in the demonstration and have students explain why the
ink in the marker is black (pigments). Show the chromatograph to the class.
3. Explain chromatography and the paper version you just demonstrated. Have students
guess what can be separated using chromatography. Explain how gases in the air and
water are separated using gas chromatography.
4. Have students come up with different ways that gas chromatography is important.
5. Tell the students that they are going to do some gas chromatography experiments. But
instead of using an expensive machine, they are going to build their own representative
machine that uses physical separation techniques.
6. Break students up into teams of 3.
7. Tell them they will be working with 6 different atoms. Give each group a “set of atoms”.
Explain that there will be 10 sample chemicals they will have to physically sort by size of
the 6 particles.
8. They will have 25 minutes to brainstorm on how to build a chromatography machine that
will separate these atoms. They must bring in all materials they need in order to build
the machine.
Day two
9. Students bring in the materials and will start building their chromatography machine.
10. In order start running their experiments, the team must demonstrate to the teacher that
the machine can separate all 6 of the atoms. Once demonstrated, they will get a
“Chemical analysis of air pollutants” student worksheet and will be able to being
determining the chemical analysis of the samples. They must use their machine. Handcounting the atoms will result in a loss of points.
11. Students will have the entire class time to build, test, and use their machine for the
experiment.
Assessment
o Students will receive a grade on the assignment using the following breakdown:
20% - Participation
30% - Completed and correct student worksheets
30% - Working chromatography machine
15% - Brought in supplies
5% - Creativity
Extension
o Have students research one of the pollutants that were tested, describing its formation and
the effects on living organisms.
o Have students find out the EPA emissions standards for chemicals tested, as well as the
levels of those chemicals in their community.
Name: ____________________________
Date: ____________
Chemical analysis of air pollutants
Student Worksheet
Sample # 1
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 2
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 3
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 4
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 5
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 6
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 7
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 8
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 9
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________
Sample # 10
Name of the pollutant: _________________________________________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Element: _____________________________
# of atoms present: ________ Atomic mass: ___________
Empirical formula: _____________________
Chemical formula: _____________________ Molecular mass: _________