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SHPE FoundationOnline SHPE Jr. Member
Activities
TeachEngineering Hands-on Activity:
*Chromatography
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SHPE Foundation
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Chromatography
• Use chromatography to separate the components of ink.
• Engineering focus: o Engineering Analysis
• Learn about the chromatography, and how it separates complex mixtures into their components, as well as how engineers use the concept of chromatography in various fields.
• Learning objectives:o Describe how chromatography works and what happens during this
process to black or colored ink.
o Explain why being able to separate solutions into their components is important to environmental engineering and water quality.
SHPE Foundation
Online SHPE Jr. Member Activities
Reference Activity on TeachEngineeringSprinkle version on TeachEngineering
• Suggested time: 45 minutes
• Materials o 1 coffee filter cut into 2-inch wide stripso 2 clear plastic cups or glasseso isopropyl alcohol (rubbing alcohol)o black and colored permanent markers (for
example, pack of Sharpies)o rulero pencilo scissorso water
SHPE Foundation
Online SHPE Jr. Member Activities
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
Engineering Connection (Real World Application):• Chromatography is a way to look at complex mixtures by separating
them into their components.
• Criminal investigators use this technology to identify substances such as chemicals, blood, ink and other fluids.
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
Engineering Connection (Real World Application):• A firm understanding of solutions and mixtures and their components is
essential for environmental engineers whose challenge is to prepare solutions to monitor and test groundwater for contaminants, and to develop remediation processes that separate pollutants from their water solutions.
o For example, engineers can use chemical oxidants to degrade certain contaminants;
o in other words, the contaminant reacts with the treatment chemical to produce a product that is benign, or harmless, unlike the contaminant.
o Some common indicators of reaction include: changes in odor, temperature, or color, production of gas, or precipitation.
o However, the only way to be absolutely certain of whether a chemical reaction has occurred is to perform a chemical analysis to determine whether a new chemical is present.
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
Vocabulary Terms
Definitions
chromatography Chromatography is a way to look at complex mixtures by separating them into their components.
solute The component of a solution in the smallest amount.
solution Mixture made of two or more substances.
solvent The component of a solution in the largest amount.
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
Background: o To increase awareness of “invisible” components in a solution (for
example: pollutants in drinking water sources), perform this exciting lab requiring you to think about how solutions and mixtures exist even in unsuspecting places such as ink!
o The separation of a mixture into its components is a physical process, i.e. because the components of the mixture are not chemically combined, they can be separated by physical means.
o For the case of ink, what are these components? We are about to find out!
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
Procedure Overview• Use alcohol, water, and coffee filters (acting as chromatography paper) to try to
separate the components of black and colored marker ink.
• For each type of ink (solute), try both water alcohol as solvents to separate the ink’s components
• Witness first-hand how components of a solution can be separated, even when those individual components are not visible in solution.
Chromatography
What do you think will happen?o Predictions
• Make a prediction for what you think will happen during the activity. What will happen when you use the black ink? Or each of the different colored inks? Will their be any differences when using alcohol vs. water?
• In each setup, identify the components of a solution (that is, solute[s] and solvent).
• Do you think a reaction will occur during the experiment? Remember the indicators of reaction (changes in odor, temperature, or color, production of gas, or precipitation.).
SHPE Foundation
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Chromatography
Procedure1.Take the strips of coffee filters and fold both pieces about
an inch from the top.
2.Use a black Sharpie to draw a horizontal line near the other end of the coffee filter strips. Make the line about as high off the bottom as the length of your thumb.
3.Use a pencil to suspend the paper in each beaker, making sure the strip does not touch the sides of the beaker.
4.Carefully add water to one cup/glass and alcohol to the other. Add just enough of each liquid so that it touches the bottom of the hanging strip.
5.Watch what happens!! Once you see the separation is complete you, get new strips and repeat using ink from a colored Sharpie marker.
6.Test other colored Sharpies to see different color separations.
SHPE Foundation
Online SHPE Jr. Member Activities
Troubleshooting Tips• Do not draw marker lines too close to the crease in the
chromatography paper. If you do, the separation takes a long time because the alcohol must travel further than if ink lines are drawn near the bottom half of the paper.
How does this activity work?? • Different inks have different properties, such as how well
they dissolve in certain types of solvents.
• When you dip a portion of the chromatography paper into the solvent, the solvent begins to move up the paper. As the solvent rises up the paper, it dissolves the ink on the paper into its components. The ink components travel up the paper with the solvent, and the distance they travel is based on how readily each component dissolves in the solvent.
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
What’s Going On? Questions during the activity
• Why doesn't the black Sharpie marker ink separate in water?
o (Answer: The separation depends on how soluble the ink in the marker is in either water or alcohol. The ink in the black marker is not soluble in water and therefore does not separate. This is also why this type of marker is considered a "permanent" marker—because it is water-insoluble and thus cannot be washed off using water! For more advanced students, explain that the alcohol is a better solvent for chromatographic separation [dissolving the ink] than water due to polar and non-polar interactions.)
• Do you see any of the indicators of reaction? Do you think that a reaction has occurred?
o (Answer: The appearance of the color components is not indicating a chemical reaction, just a separation. One indication that a reaction has not occurred is that no energy change has taken place. All of the indicators of reaction correspond to an energy change.)
Chromatography
SHPE Foundation
Online SHPE Jr. Member Activities
What happened during the experiment?• What were the two solvents used in our lab activity today?
o (Answer: Water and isopropyl alcohol.)
• Black ink is more attracted to which solvent? How do you know? o (Answer: The black ink is more attracted to the isopropyl alcohol. We observed ink
separation in the isopropyl alcohol and no ink separation in the water.)
• What colors are present in black ink? o (Answer: This varies from group to group, but typically the most common colors are
purple, blue and yellow. In addition, black is still visible in the separation.)
• What do these colors represent?o (Answer: Each color represents the different solutes or ink components used to
make the black ink. We cannot see each of these individual components unless a separation occurs. This separation only occurs when a solvent is used in which the ink is soluble.)
• Why might the ability to separate solutions into their components be important to environmental engineers and water quality?
o (Answer: Environmental engineers must understand all about solutions and mixtures and their components because most experiments and data gathering done for the purpose of improving groundwater quality involve the preparation of solutions to monitor and test contaminated water. Only if we can separate from water the usually invisible water pollutant chemicals can we design remediation methods to clean the water!)
Chromatography
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o over 1,300 standards-based engineering lessons and activities
• Carleigh Samson, TeachEngineering Editoro [email protected] 303.492.6950
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