Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. To prepare 100 mL of individual dye solutions, add 0.5 g of each FD&C solid dye to a separate beaker with 100 mL of distilled or deionized water. Mix thoroughly.
2. To prepare the dye mixture for the Introductory Activity, combine 10 mL of Red No. 40, Blue No. 1 and Yellow No. 5 dye solutions in one beaker.
3. To prepare 500 mL of 2% sodium chloride solution, fill a 500-mL volumetric flask one-third to one-half full with distilled or deionized water. Add 50 mL of 20% NaCl solution and dilute with distilled or deionized water to the mark. Mix thoroughly.
4. To prepare 500 mL of 2% isopropyl alcohol solution, measure 14.3 mL of 70% isopropyl alcohol solution. Pour this into a 500-mL volumetric flask and dilute with distilled or deionized water to the line. Cover and mix thoroughly before dispensing.
5. See the Lab Hints section for suggestions for unknown mixtures of dyes.

Safety Precautions

Isopropyl alcohol is a moderate fire risk and is slightly toxic by ingestion or inhalation. Use proper exhaust ventilation to keep airborne concentrations low. The FD&C dyes are slightly hazardous by ingestion, inhalation and eye or skin contact. Red No. 40 may be absorbed through skin and Yellow No. 5 may be a skin sensitizer. All dyes are irritating to skin and eyes. Avoid contact with eyes, skin and clothing. Wear chemical splash goggles, chemical-resistant glove and a chemical-resistant apron. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Excess dye solutions and sodium chloride solution may be stored for future use or rinsed down the drain with excess water according to Flinn Suggested Disposal Method #26b. Small quantities of excess isopropyl alcohol solutions may be rinsed down the drain with excess water according to Flinn Suggested Disposal Method #18a.

Lab Hints

• Enough chromatography paper strips are included for 12 groups of students to develop 16 chromatograms each. Extra strips are provided in case of mistakes.
• Students should avoid over-handling the chromatography strips. Oil from the skin can interfere with the capillary action that draws water through the paper.
• In the Introductory Activity portion of the lab, it is recommended that half of the groups use 2% sodium chloride solution as the developing solvent and the other half use 2% isopropyl alcohol as the developing solvent. This split will allow for adequate testing of both solvents, providing enough data for students to compare benefits and drawbacks of both solvents.
• Good technique is important to achieve clean separations in paper chromatography. Common sources of student error include “overloading” the paper by placing too much dye on the initial spot and the band broadening that occurs because the initial spot is too large.
• Suggestions for unknown dye mixtures follow. The blue, red and yellow mixtures are suggested for identification of dyes found in commercial food products. Mix equal volumes of each dye desired to create a mixture.
  • Purple: Combine Blue No. 1 and Red No. 3, or Blue No. 2 and Red No. 3 or Blue No. 1 and Red No. 40.
  • Orange: Combine Red No. 40 and Yellow No. 6.
  • Green: Combine Blue No. 2 and Yellow No. 6; or Blue No. 1 and Yellow No. 6; or Blue No. 1, Yellow No. 5 and Green No. 3; or Blue No. 2, Yellow No. 6 and Green No. 3.
  • Blue: Combine Blue No. 1 and Blue No. 2.
  • Red: Combine Red No. 3 and Red No. 40.
  • Yellow: Combine Yellow No. 5 and Yellow No. 6.
• It is critical to allow enough time for the development of the chromatography paper. The chromatography paper must be left in the chromatography chamber long enough for the solvent to be drawn up near the top of the strip. Do not stop the development until the solvent front nears the top of the strip. Underdevelopment will lead to incomplete separation. Do not allow the solvent front to move off the paper, however.
• The developing solvent and dyes will continue to move even after the paper strip is removed from the solvent. It is necessary for students to mark the solvent front and positions of the dye bands or spots immediately after the strip is removed from the flask.|As students plan their investigation in the inquiry portion, they must remember to run a control or baseline trial. The 2% sodium chloride and 2% isopropyl alcohol solutions are convenient baseline runs because those were used in the Introductory Activity.
• See the last page of the Instructor’s Notes for chemical structures of the seven FD&C food dyes. Provide these to the students as they work through the Guided-Inquiry Design portion of the lab.
• When the food dyes are dissolved in water, the sodium salts of the sulfonate, oxide and carboxylate groups dissociate to give negatively charged side groups.
• The test solvents used in the Introductory Activity have different polarities. The isopropyl alcohol solution decreases the polarity of pure water because isopropyl alcohol is only slightly polar. The three-carbon chain is mostly nonpolar and the oxygen in the alcohol group draws electrons to itself giving rise to a partial negative charge. The sodium chloride solution increases the polarity of pure water. In addition to having the highly polar water molecules, the solution contains dissociated sodium and chloride ions.
• The best solvent is not necessarily the solvent that provides the largest R_f values. The optimal solvent will provide the greatest ratios of Rf values among the dyes. This means the separation or resolution of the component dyes relative to each other is maximized.
• Expand the students’ chromatography repertoire by separating dye components through column chromatography with the Liquid Chromatography—Student Laboratory Kit available from Flinn Scientific, Catalog No. AP9093.

Further Extensions

Opportunities for Undergraduate Research
As noted in the Background section, FD&C food dyes are used in a wide range of food products, most notably the outer shells of candies. Candy may be placed in 5–6 drops of water. Stir the candy until the color dissolves. Repeat with two more candies. This is the color sample. Design an experiment to determine the composition of the dye mixture in the candy shell.

Answers to Prelab Questions

1. Figure 1 is a sample paper chromatogram for three samples: A, B and C. Label the drawing with the following items: the stationary phase, the mobile phase and the solvent front.
2. Calculate the R_f value for the spot in sample B using sample A as an example.
   {13995_PreLabAnswers_Figure_2}
3. Sample C gave two spots on the paper chromatogram. What does this tell you about the composition of the sample?

   Sample C is a mixture of at least two components, A and B.

4. Based on the R_f values of samples A and B, what can you conclude about the intermolecular attractions both samples have for the eluent and the paper?

   The R_f value of sample A is larger than sample B. Sample A has a stronger affinity (attraction) for the eluent (solvent) than the paper, so it traveled farther with the solvent. Sample B has a stronger attraction for the paper than the solvent, so it traveled a shorter distance.

Sample Data

Introductory Activity

Observations for 2% Sodium Chloride Solution

Total time for chromatograms to develop ranged from 25–30 minutes. Three separate dye spots were visible: blue on top, yellow in the middle, and red on the bottom. Each spot was fairly spread out, with the largest band being the Blue No. 1 dye. All three dyes traveled the same direction in a straight line (not curved).

Observations for 2% Isopropyl Alcohol Solution Total time for chromatograms to develop ranged from 25–30 minutes. Two separate dye spots were visible: blue and yellow on top, and red on the bottom. The Blue No. 1 and Yellow No. 5 colors overlapped resulting in a blue front followed by a green line then a yellow tail end. The blue-yellow color band traveled straight for a portion of the time, and then the edges began trailing while the middle continued at a “faster” rate. The shape of the blue-yellow color band was a crescent. The top of the Red No. 40 color spot was near the middle of the crescent.

Guided-Inquiry Activity

Comparison of Solvent Concentration on Dye Mixture Separation
Based on the data and observations of the Introductory Activity, the sodium chloride solvent was chosen for further investigation. The concentration of the solvent was increased by a factor of four to 8% and decreased by a factor of four to 0.5%. The following data table summarizes the findings.

*Values are averaged from two trials each.
†R_f values are copied from Introductory Activity here for comparison.

In the 8% sodium chloride solvent, total time for chromatograms to develop ranged from 20–30 minutes. All three dyes were visible: blue on top, yellow in the middle and red on the bottom. Blue No. 1 was the largest band. The Yellow No. 5 band overlapped with roughly half of the Red No. 40 band. These two bands were much closer than in the 2% sodium chloride solvent. All three dyes traveled in the same direction in a straight line (not curved).

In the 0.50% sodium chloride solvent, the total time for chromatograms to develop ranged from 20–30 minutes. The three dyes were visible: blue on top, yellow in the middle, and red on the bottom. Red No. 40 was the largest band. The Yellow No. 5 band overlapped with the very top of the Red No. 40 band. These two bands were much closer than in the Introductory Activity. All three dyes traveled in the same direction in a straight line (not curved).

Based on the data collected for the 8% and 0.50% sodium chloride solutions, the more dilute solvent separated the mixture of dyes better. The three dyes were more distinguishable from one another in the 0.50% solution than in the 8% solution. This was evident with the overlapping of the Yellow 5 and Red 40 dyes with the 8% solvent. The 0.50% sodium chloride solution was the more optimal solvent, compared to the 2% and 8% solutions, because the dyes traveled farther on the paper and there were greater distances separating the dye bands.

Effect of Solvent Concentration on FD&C Food Dyes
The following chart is a comparison of the seven FD&C food dyes at two different concentrations of sodium chloride solutions: 2% and 0.10%. The 0.10% concentration was chosen based on the work of Peter Markow (see the Reference section). The dyes were run simultaneously on the same piece of chromatography paper. Green No. 3 and Blue No. 1 have very similar R_f values in both 2% and 0.10% sodium chloride solutions. Similarly, Red No. 40 and Blue No. 2 have similar R_f values in the two sodium chloride solutions. These two pairs of dyes will be the most difficult to separate.

Answers to Questions

Guided-Inquiry Design and Procedure Questions

1. Examine the structures of the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 dyes. What are the similarities and differences in the structures of the three dyes?

   All three dyes, Red No. 40, Blue No. 1 and Yellow No. 5, have sulfonate (—SO₃¯) functional groups. However, Blue No. 1 has the most sulfonate groups (three); Red No. 40 and Yellow No. 5 both have two. Blue No. 1 also has a positively charged nitrogen atom and Yellow No. 5 has a carboxylate group (—CO₂^–). Red No. 40 and Yellow No. 5 both have double bonded nitrogen atoms near the middle of the structures and a single —OH group. Red No. 40 has an —OCH₃ group and a methyl group on the leftmost benzene ring. Blue No. 1 is the largest molecule of the three dye molecules.

2. In the Introductory Activity, the developing solvents were 2% sodium chloride aqueous solution and 2% isopropyl alcohol aqueous solution. Draw separate molecular diagrams of how sodium chloride and isopropyl alcohol would interact in water. Identify the types of intermolecular attractions within each diagram.
   {13995_Answers_Figure_1}
3. Based on the diagrams and intermolecular attractions identified in Question 2, predict and compare the nature of intermolecular attractions experienced by the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 dyes with the two solvents.

   In the sodium chloride solution, all three dye molecules would experience ion–dipole interactions due to the charged sulfonate groups, although the overall strength of these interactions will vary due to the number of groups on each molecule. Similarly, each dye molecule will experience hydrogen bonding between water and the functional groups. Blue No. 1 would experience the strongest interactions because it has the most charged side groups—three SO₃^– groups and a positively charged nitrogen atom. Red No. 40 and Yellow No. 5 would experience weaker ion–dipole and hydrogen bonding interactions with the sodium chloride solution because the molecules have fewer charged side groups. Yellow No. 5 experienced a stronger interaction with the sodium chloride solution because it has a charged carboxylate group in addition to two charged sulfonate groups. Red No. 40 only has two charged sulfonate groups.
   
   In the isopropyl alcohol solution, all three dye molecules would experience ion–dipole interactions due to the charged functional groups and polar alcohol group in isopropyl alcohol. In addition to their changed side chains, all of the food dyes are large organic molecules with significant nonpolar rings and groups. These nonpolar regions interact with relatively nonpolar isopropyl alcohol molecules and thus have a greater affinity for this solvent than for either the NaCl solution or the hydrophilic paper substrate.

4. Chromatography paper, and paper in general, is highly hydrophilic. Paper is made from a natural polymer called cellulose, which is a long chain of glucose molecules. Glucose is a cyclic structure with a number of —OH groups around the ring.
   1. Predict and explain the types of intermolecular forces that would occur between paper and water. How do these interactions account for the hydrophilic nature of paper?

      The —OH groups around the glucose rings are sites for ion–dipole interactions and hydrogen bonding with water. The hydrogen bonding interaction between the paper and water will be strong because the —OH groups will be able to interact strongly with the hydrogens and oxygen in water due to the large dipole moments. Paper has a strong affinity for water and draws water up by capillary action.

   2. Explain the types of intermolecular interactions that would occur between the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 food dyes and the paper.

      The —OH groups around the glucose rings are sites for hydrogen bonding with the charged functional groups on the dye molecules. In addition, Red No. 40 would experience hydrogen bonding at the —OH group and —OCH₃ group. Yellow No. 5 would have hydrogen bonding at the —OH group, as well. In both Red No. 40 and Yellow No. 5, hydrogen bonding would occur with the double-bonded nitrogen atoms and —OH groups around the glucose rings.

Post-Laboratory Review Questions

1. Hydrocarbons are nonpolar compounds containing carbon and hydrogen atoms. The properties of three hydrocarbons are summarized.
   {13995_Answers_Table_1}
   1. How do the attractive forces between molecules change in the transition from the gas to the liquid to the solid state?

      Attractive forces between molecules increase in the order gas <>< liquid < solid. Molecules in the gas state are very far apart—there are almost no attractive forces between the molecules. As gases condense into liquids and then solidify, the molecules get closer together and the strength of attractive forces between molecules increases. Attractive forces between molecules are strongest in the solid state, because the molecules are locked into fixed positions.

   2. Based on its properties, which compound has the strongest attractive forces? The weakest attractive forces?

      Eicosane, a hydrocarbon with 20 carbon atoms, has stronger intermolecular attractive forces than octane or methane, which contain eight carbon atoms and one carbon atom, respectively. Methane has the weakest attractive forces.

   3. Write a general statement describing how the size of a molecule influences the strength of London dispersion forces between molecules.

      The strength of London dispersion forces between molecules increases as the size of the molecules increases (all other factors being equal).

2. Dyes are organic compounds that can be used to impart bright, permanent colors to fabrics. The affinity of a dye for a fabric depends on the chemical structures of the dye and fabric molecules and also on the interactions between them. Three common fabrics are wool, cotton and nylon. Wool is a protein, a naturally occurring polymer made up of amino acids with ionized (charged) side chains. Cotton is a naturally occurring polymer made up of glucose units with hydrophilic groups surrounding each glucose unit. Nylon is a synthetic polymer made of hydrocarbon repeating chains joined together by highly polar amide (–CONH–) functional groups.
   1. The chemical structure of methyl orange is drawn. Identify the groups in the dye that will bind to ionic and polar sites in a fabric.
      {13995_Answers_Figure_3}
   2. Complete the following “If/then” hypothesis to explain how the structure of a fabric will influence the relative color intensity produced by methyl orange.

      “If a fabric contains more ionic and polar groups in its structure, then the intensity of the dye color due to methyl orange should increase, because there would be more sites on the fabric for the dye molecules to bind.”

   3. Using this hypothesis, predict the relative color intensity that would be produced by methyl orange on cotton, nylon and wool. Rank the fabrics from 1 = lightest color to 3 = darkest color.

      1 = nylon, 2 = cotton, 3 = wool

Discussion

Chemical Structures of FD&C Food Dyes

References

Markow, P. G. The Ideal Solvent for Paper Chromatography of Food Dyes. J. Chem. Ed. 1988, 65, 10, pp 899–900.

Introduction

The entire palette of artificial food colors is derived from just seven dyes certified by the FDA for use in food, drugs, and cosmetics. How can these FD&C dyes be identified in a mixture? How do the molecular structures of the dye molecules influence their properties, including their relative solubility or affinity for different solvents?

Concepts

• Chromatography
• Polarity
• Food chemistry
• R_f values
• Intermolecular forces

Background

The use of color additives increased dramatically in the United States in the second half of the nineteenth century. As the economy became more industrial, demographics shifted, fewer people lived on farms, and city populations grew. People became more dependent on mass-produced foods.

Color additives were initially used to make food more visually appealing to the consumer and, in some cases, to mask poorquality, inferior or imitation foods. For example, meat was colored to appear fresh long after it would have naturally turned brown. Jams and jellies were colored to give the impression of higher fruit content than they actually contained. Some food was colored to look like something else—imitation crab meat, for example. Many of the food colorings and additives were later discovered to be harmful or toxic.

In 1883, the United States Department of Agriculture (USDA) Bureau of Chemistry began regulating the food industry to help ensure a safe food supply. Food coloring regulation is just one example of the agency’s efforts. Food colorants were being added to food with little or no health testing. To propagate the food safety effort, in 1906 the USDA hired a consultant, Dr. Bernard Hesse, to determine colorants that would be safe to consume in food. In 1907, the number of synthetic food dyes approved for use in the United States was reduced from 695 to just seven. As additional data was collected through consumer reports and laboratory testing, more dyes were eliminated or restricted. Only two of the original dyes from 1907 are still accepted for use today. Five others were added between 1907 and 1971. In total, only seven dyes color all U.S. food today. All of the FD&Capproved food dyes are charged, water-soluble organic compounds that bind to natural ionic and polar sites in large food molecules, including proteins and carbohydrates.

Chromatography is one of the most useful methods of separating and purifying organic compounds. There are many different types of chromatography but most depend on the principle of adsorption. The two important components of chromatography are the adsorbent and the eluent. Adsorbents are usually solid materials that will attract and adsorb the materials to be separated. The eluent is the solvent, which carries the materials to be separated through the adsorbent.

Chromatography works on the concept that the compounds to be separated are slightly soluble in the eluent and will spend some of the time in the eluent (or solvent) and some of the time on the adsorbent. When the components of a mixture have varying affinities for the eluent, they can then be separated from one another. The polarity of the molecules to be separated and the polarity of the eluent are very important. Changing the polarity of the eluent will only slightly affect the solubility of the molecules but may greatly change the relative attraction for the adsorbent. Affinity of a substance for the eluent versus the adsorbent allows molecules to be separated by chromatography.

Paper chromatography is often used as a simple separation technique. In paper chromatography, the adsorbent is the paper itself, while the eluent can be any number of solvents. When the paper is placed in a chromatography chamber, the eluent moves up the strip by capillary action. Organic molecules that are “spotted” onto the paper strip separate as they are carried with the eluent at different rates. Those molecules that have a polarity closest to the polarity of the eluent will move up the strip the fastest.

The choice of the eluent is the most difficult task in chromatography. Choosing the right polarity is critical because this determines the level of separation that will be achieved. Different samples will spend varying amounts of time interacting with the paper and the solvent. Through these different interactions, the samples will move different distances along the chromatography paper. The distance a sample moves along the chromatography paper is compared to the overall distance the solvent travels—this ratio is called the R_f value or rate of flow.

Experiment Overview

The purpose of this inquiry lab is to investigate the factors that influence the separation of food dyes using paper chromatography. The investigation begins with a baseline activity comparing the separation or resolution of three FD&C dyes, Red No. 40, Blue No. 1 and Yellow No. 5, using two solvents. Reviewing the evidence provided by the cooperative class data leads to the selection of a solvent for further study. In the guided-inquiry section of the lab, students will design an experiment to identify a solvent that will give maximum resolution of a mixture of dyes. The results may be applied to study the connection between structure and mobility of food dyes. An investigation into the composition of colored candy shells may be incorporated as an optional extension activity.

Materials

Prelab Questions

1. Figure 1 is a sample paper chromatogram for three samples: A, B and C. Label the drawing with the following items: the stationary phase, the mobile phase and the solvent front.
   {13995_PreLab_Figure_1}
2. Calculate the R_f value for the spot in sample B using sample A as an example.
3. Sample C gave two spots on the paper chromatogram. What does this tell you about the composition of the sample?
4. Based on the R_f values of samples A and B, what can you conclude about the intermolecular attractions both samples have for the eluent and the paper?

Safety Precautions

Isopropyl alcohol is a flammable liquid and is slightly toxic by ingestion or inhalation. Use proper exhaust ventilation to keep airborne concentrations low. The FD&C dyes are slightly hazardous by ingestion, inhalation and eye or skin contact. Red No. 40 may be absorbed through skin and Yellow No. 5 may be a skin sensitizer. All dyes are irritating to skin and eyes. Avoid contact with eyes, skin and clothing. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory. Please follow all laboratory safety guidelines.

Procedure

Introductory Activity

1. Position the chromatography paper strip so it is 152 mm tall and 19 mm wide. Note: Handle the paper by the edges so the analysis area is not accidentally compacted or contaminated.
2. Using a ruler and a pencil, draw a faint line 15 mm from the bottom of the paper across the width of the strip. Measure 9.5 mm from the edge and place a dot on the line. This is the starting point for the sample.
3. Using the same ruler, measure 20 mm from the top of the strip and fold across the width of the strip. This will allow the strip to hang on the lip of the flask.
4. Repeat steps 2 and 3 for a second paper strip.
5. Obtain the dye mixture.
6. Using a clean toothpick, spot the chromatography strip by placing a toothpick into the dye mixture solution and then touching the tip of the toothpick gently onto the designated pencil dot. Allow the sample to dry. Repeat the procedure two to three more times. Note: This step is necessary to increase the concentration of the sample but do not allow the size of the spot to increase.
7. Repeat step 6 for the second chromatography strip.
8. While the samples are drying, obtain two 250-mL Erlenmeyer flasks and watch glasses.
9. Pour 20 mL of the assigned 2% chromatography solvent into each flask. Cover the flasks with the watch glasses.
10. Once the chromatography paper is dry, remove the watch glass from the top of the flask. Carefully hang the chromatography strip into the flask with the sample end down. Do not get any solvent on the upper portion of the strip. The sample spots must remain above the level of the solvent. If the solvent level is too high, the samples will dilute into the solvent!
11. Carefully place the watch glass back on the top of the flask. Allow the chromatogram to develop. Record observations of the dye sample as the solvent travels up the paper and the chromatogram develops.
12. Repeat steps 10 and 11 using the other chromatography strip and flask.
13. When the chromatography solvent is within 1–2 cm of the fold in the chromatography strip, stop the run by removing the strip from the flask.
14. With a pencil, lightly draw a line to mark the distance the solvent traveled. This is called the solvent front.
15. Measure the distance from the pencil line at the bottom of the strip to the solvent front. Record this distance in millimeters in an appropriate data table.
16. With a pencil, trace the shape of each dye band or spot to mark its location on the chromatography strip. This should be done immediately because the color and brightness of some spots may fade over time.
17. Measure and record the distance in millimeters that each dye band or spot traveled. Measure from the line at the bottom of the paper to the center of each band or spot.
18. Repeat steps 13–17 for the other chromatograms.

Analyze the Results
Compile the class data and calculate the average R_f value for each dye in both solvents. Compare observations regarding the separation using the different solvents, including developing time, color spreading and direction of travel.

Guided-Inquiry Design and Procedure
Form a working group with other students and discuss the following questions.

1. Examine the structures of the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 dyes. What are the similarities and differences in the structures of the three dyes?
2. In the Introductory Activity, the developing solvents were 2% sodium chloride aqueous solution and 2% isopropyl alcohol aqueous solution. Draw separate molecular diagrams of how sodium chloride and isopropyl alcohol would interact in water. Identify the types of intermolecular attractions within each diagram.
3. Based on the diagrams and intermolecular attractions identified in Question 2, predict and compare the nature of intermolecular attractions experienced by the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 dyes with the two solvents.
4. Chromatography paper, and paper in general, is highly hydrophilic. Paper is made from a natural polymer called cellulose, which is a long chain of glucose molecules. Glucose is a cyclic structure with a number of —OH groups around the ring.
   1. Predict and explain the types of intermolecular forces that would occur between paper and water. How do these interactions account for the hydrophilic nature of paper?
   2. Explain the types of intermolecular interactions that would occur between the FD&C Red No. 40, Blue No. 1 and Yellow No. 5 food dyes and the paper.
5. Write a detailed step-by-step procedure using dilutions of more concentrated solvents to investigate the effect of concentration on dye separations in various unknown dye mixtures.
6. Include all materials, glassware and equipment that will be needed, safety precautions that must be followed, the concentrations of the solvents, etc.
7. Review additional variables that may affect the reproducibility or accuracy of the experiment and how these variables can be controlled.
8. Carry out the experiment and record the results in an appropriate data table.

Analyze the Results
Compile the data within your group. Identify the optimal solvent tested by your group. Propose an explanation for why the chosen solvent was best.

Student Worksheet PDF

13995_Student1.pdf