Category: My Classroom Material

Paper Chromatography of Ink

Paper Chromatography of Ink

Introduction:

The colors in magic markers are often due to a mixture of several compounds.  These inks can be separated using paper chromatography.  Porous paper serves as the stationary phase.  Depending on the type of ink, the mobile phase will vary.  Permanent inks require isopropyl alcohol to separate, while washable markers require only water.  After separation, one can observe the different colors that make up a particular color of magic marker.

Purpose:

The purpose of this experiment is to separate the inks in magic markers using paper chromatography.

Materials:

Chromatography tubes, assorted permanent & water-soluble markers, water, metric ruler, chromatography paper or coffee filters, scissors, isopropyl alcohol

Safety:

 

Procedure:

  1. Always wear safety glasses and an apron in the lab
  2. Obtain a chromatography tube & cap (one for each marker to be tested).
  3. Cut strips of chromatography paper slightly longer than the test tubes and slightly narrower than the slit in the cap.
  4. In the center of each strip about 3 cm from the pointed end, place a dot of the marker to be tested.  The dot should be about 0.2 cm in diameter and dark enough to be clearly visible.
  5.  Place about 1 -1.5 cm of water in each test tube.
  6. Put the strip through the chromatography cap so that it is suspended from the cap.
  7.  Carefully insert the chromatography paper into the test tube, dotted end down.  The dot must be above the water, and the sides of the chromatography paper cannot touch the sides of the test tube.
  8. Allow the test tube to remain undisturbed until a good separation is obtained or until the solvent front reaches the top of the test tube.  In a good separation, the colors are separated and the solvent is clearly above the top color.
  9.  Remove the chromatogram.
  10. Mark the solvent front with a pencil. (Do this before the solvent dries!)
  11. Calculate the Rf values (Rf = distance solute moved/distance solvent moved).
  12.  Repeat for as many different colors as assigned.
  13. Repeat using isopropyl alcohol as the solvent.

Data Table:  

Marker color and brand _________________________________________

 

Colors observed top to bottom
(Solvent – water)		 Rf Value Colors observed top to bottom
(Solvent – Alcohol)		 Rf Value

 

Marker color and brand __________________________________________

 

Colors observed top to bottom
(Solvent – water)		 Rf Value Colors observed top to bottom
(Solvent – Alcohol)		 Rf Value

 

 

Questions:

1.  What marker colors were mixtures?  

2.  Why is isopropyl alcohol a better mobile phase than H2O for permanent markers?  

3.  Why does the spot need to be above the level of the solvent when the chromatogram is placed into the solvent?

Natural Selection Activity

 

Survival of the Fittest

 

Introduction:

  Within a population, organisms will vary.  Charles Darwin stated that in the struggle for existence, those variant organisms that have favorable variations are “better adapted” to their environment and will survive and reproduce in greater numbers.  Favorable variations may mean that they are faster, or stronger, or able to eat different types of food, or better camouflaged to avoid predators.  In this lab you will simulate the effect of predation by a hawk on a large population of assorted mice.  Your population of mice will consist of black, white, and speckled mice.  You will represent the hawk.

Objectives:

  –to simulate the effect of hawk predation on the appearance of mice
-to simulate the natural selection of traits

Materials:

large sheet of newspaper  4 hawks (students)
30 white mice (paper squares) 1 petri dish
30 speckled mice (paper squares)
30 black mice (paper squares)

Procedure:

  1. Open your sheet of newspaper and place it on the lab table.  This will serve as the environment for your mice.
  2. Place the petri dish on the other side of the lab table.  This will be the nest.
  3. Select one person from your group to act as a hawk.  This person should stand by the nest.
  4. Spread the mice on their environment evenly.
  5. The hawk now swoops over and has 1 minute to pick up as many mice as possible. The hawk may only pick up one mouse at a time, and must place it in their nest (a petri dish) before flying back to pick up another.  The goal is to pick up as many mice as possible in the time period.
  6. When the time is up record the number of mice left in the environment in the data table below.
  7. Repeat this procedure for each person in the lab group or 4 times. 
  8. After all data is collected, construct a bar graph. Be sure to label the graph and its axes.
  9. Data:

 

White
mice
Speckled mice
Black
mice
Hawk #1  

 
Hawk #2  

 
Hawk #3  

 
Hawk #4  

 
Total  

 

 

Conclusion:
 Write a paragraph describing;

* the purpose of the lab

* what you thought the results would be

* what the results were (discussing numbers from data)

*how the mouse population and hawk population may change over time from natural selection

 

Paper Chromatography Report

 

 

Paper Chromatography

 

 

Introduction
The purpose of this experiment is to observe how chromatography can be used to separate mixtures of chemical substances. Chromatography serves mainly as a tool for the examination and separation of mixtures of chemical substances. Chromatography is using a flow of solvent or gas to cause the components of a mixture to migrate differently from a narrow starting point in a specific medium, in the case of this experiment, filter paper. It is used for the purification and isolation of various substances. A chromatographically pure substance is the result of the separation. Because purification of substances is required to determine their properties, chromatography is an indispensable tool in the sciences concerned with chemical substances and their reactions.

Chromatography is also used to compare and describe chemical substances. The chromatographic sequence of sorbed substances is related to their atomic and molecular structures. A change in a chemical substance produced by a chemical or biological reaction often alters the solubility and migration rate. With this knowledge, alterations or changes can be detected in the substance.

In all chromatographic separations, there is an important relationship between the solvent, the chromatography paper, and the mixture. For a particular mixture, the solvent and the paper must be chosen so the solubility is reversible and be selective for the components of the mixture. The main requirement, though, of the solvent is to dissolve the mixture needing to be separated. The porous paper used  must also absorb the components of the mixtures selectively and reversibly. For the separation of a mixture, the substances making up the mixture must be evenly dispersed in a solution, a vapor, or a gas. Once all of the above criteria have been met, chromatography can be a simple tool for separating and comparing chemical mixtures.

 

Hypothesis
Paper can be used to separate mixed chemicals.

 

Materials
The materials used for this lab are paper, pencil, eraser, filter paper, test tube, rubber stopper, paper clip, metric ruler, black felt-tip pen, and a computer.

 

Methods
The first step of the method is to bend a paper clip so that it is straight with a hook at one end. Push the straight end of the paper clip into the bottom of the rubber stopper. Next, you hang a thin strip of filter paper on the hooked end of the paper clip. Insert the paper strip into the test tube. The paper should not touch the sides of the test tube and should almost touch the bottom of the test tube. Now you will remove the paper strip from the test tube. Draw a solid 5-mm-wide band about 25 mm from the bottom of the paper, using the black felt-tip pen. Use a pencil to draw a line across the paper strip 10 cm above the black band.

Pour about 2 mL of water into the test tube. The water will act as a solvent. Put the filter paper back into the test tube with the bottom of the paper in the water and the black band above the water. Observe what happens as the liquid travels up the paper. Record the changes you see. When the solvent has reached the pencil line, remove the paper from the test tube. Measure how far the solvent traveled before the strip dries. Finally, let the strip dry on the desk. With the metric ruler, measure the distance from the starting point to the top edge of each color. Record this data in a data table. Calculate a ratio for each color by dividing the distance the color traveled by the distance the solvent traveled.

 

Results
The results of the experiment are shown in a chart and a graph.

Color of Ink (listed in order) Distance each Color Traveled (mm) Distance Solvent Traveled (mm) Ratio Traveled
(Distance color moved divided by distance solvent moved)
Yellow 70 mm 111 mm .63
Pink 82 mm 111 mm .74
Red 101 mm 111 mm .91
Purple 110 mm 111 mm .99
Blue 111 mm 111 mm 1.0

Questions

 

1. How many colors separated from the black ink? Five colors separated from the black ink: yellow, pink, red, purple, and blue.

2. What served as the solvent for the ink? Water served as the solvent for the ink. As the solvent traveled up the paper, which color of ink appeared first? The color orange first appeared as the solvent traveled up the paper.

3. List the colors in order, from top to bottom, which separated from the black ink. The colors separated in this order, from top to bottom: blue, purple, red, pink, and then yellow.

4. In millimeters, how far did the solvent travel? The solvent traveled 111 mm.

5. From your results, what can you conclude is true about black ink? Black ink is a mixture of several different colors.

6. Why did the inks separate? The inks separated because the black ink was a mixture of different pigments with different molecular characteristics. These differences allow for different rates of absorption by the filter paper.

7. Why did some inks move a greater distance? The ink least readily absorbed by the paper would then travel the farthest from the starting mark. You can conclude from this information that the different pigments were absorbed at different rates.

 

Error Analysis
Possible errors could include inaccurate measurements of the distances traveled by the inks and mistakes when calculating the ratio traveled by the water and colors. If a longer test tube was used, a longer strip of filter paper could have been used. This may have changed the ratios. Another color may have been present, but not detected because of the filter paper length.

 

Conclusion
The proposed hypothesis was correct. The paper chromatography did show that black ink could be separated into various colors. The black ink gets its color from a mixture of various colored inks blended together. The first color of ink to appear on the filter paper was yellow followed by pink, red, purple then blue. The colors separated the way they did because of the differences in their molecular characteristics, specifically, their solubility in water and their rate of absorption by the paper. The most soluble and readily absorbed ink color was the yellow. The least soluble and least absorbable ink color was the blue.

Back

 

Natural Selection Peanut Activity

 

Natural Selection Within a Species

 

Introduction:

Natural selection is the evolutionary process by which the most adaptable individuals survive. An adaptation is an inherited variation that helps an organism to survive. When the organism survives, its chances of reproduction are increased as well as its ability to pass on its inherited traits.  All members of a species are different from one another.  In this activity, you will investigate two variations among peanut plants — length of shell and number of seeds per shell.   Most shells contain a certain number of seeds which is an adaptation to its survival.  

Objective:

Students will investigate natural selection in peanuts.

Materials:

50 peanuts in shells, metric ruler, pencil, graph paper

Procedure:

  1. Count out 50 peanuts in their shells.
  2. Use a metric ruler to measure the length of each shell in millimeters.  Put a check mark in Table 1 in the space indicating the length of the shell.
  3. Open the shell and count the number of seeds inside.  Put a check mark in Table 2 in the space next to the number of seeds that you counted. 
  4. Repeat steps 1 – 3 for the other 49 peanuts.
  5. Set up two bar graphs using the headings from each table as the axes for each graph.
  6. Plot a bar graph from the data in each table.

Data:

Table 1

 

Length of Shell
(mm)		 Number of Shells
5-10
10-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
50-55
55-60
60-65
65-70
70-75

 

 

Table 2

 

Number of Seeds Per Shell Number of Shells
1
2
3

 

 

 

Title: ________________________________________________________

 

Title: ________________________________________________________

 

Questions:

  1. What is the most common length of the shells you measured?
  2. What was the most common number of seeds in the peanut shells that you opened?
  3. What might happen if each shell contained fewer than normal seeds and why?
  4. What might happen if each shell contained more than the normal number of seeds and why?
  5. Was there a relationship between the most common length of shells and the number of seeds they contained? Explain your answer.
  6. Write 1-2 paragraphs explaining how shell length and seed number in peanuts illustrates natural selection within this species.