CHEM 211-2007
2
Experiment 4
How and Why Do
Substances
Dissolve?
Solutes
Solvents
G. General Overview of the Experiment:
You will work in groups of three or four with a manager, a recorder, a presenter and when
possible a technician.
 Each group member will be assigned a different set of 4 alcohol solutes contained in
dropping bottles and the group will be assigned 1 organic solvent. (See the lab section
page on the course website for individual alcohol solute assignments and group
organic solvent assignment.) Models of water and the organic solvent molecules will be
available in the laboratory.
 Groups choose a name
 Individuals build models of their alcohols
 Group members collaborate on developing one or more specific predictions as to trends
in solubility behavior of their alcohols in water and their assigned organic solvent.
Bondline structural formulas of all organic solvents and alcohol solutes are provided in
Tables 1 & 2 at the end of this handout.
 Groups then obtain their alcohols and test predictions by doing solubility tests.
 After collecting data, students analyze their own data
 Group members then compare results within the group, reconsider their original
predictions and develop a hypothesis, based on intermolecular interactions, to explain the
observed trends in solubility behavior of alcohols in water and organic solvents.
 Finally, groups test their understanding of solubility by comparing results with another
group that used a different organic solvent and explaining those additional results.
H. Procedure:
1. During the first 5 minutes of the lab period, choose a group name.
2. Read the entire procedure. Manager: Assure that all group members understand the goal
of the experiment and what is to be done.
3. Build models of your assigned alcohol solute molecules.
4. Record the specific waste disposal instructions for the compounds you will use for the
experiment. (See the waste disposal instructions for all compounds in Tables 1 & 2)
Note also that all aqueous (water) solutions of category 4 compounds are disposed in
the special Aqueous-Organic waste container for Experiment 4.
5. While waiting for your other group members to complete their models, write the
procedure and prepare solubility results tables to record your 2 sets of solubility results
and observations (Aqueous & Organic solvents, see procedure steps 11-17) in your results
section. (See the models in Tables 3 & 4) Be sure to include specific names of all
compounds you are using in your procedure and to allow sufficient space between your
procedure steps to accommodate each table.
Solubility
3
CHEM 211 Experiment 4
6. Collaborate with your group mates to compare the models of the various solute molecules
with those of your group organic solvent and water.
7. Develop specific predictions on the trend in relative solubilities of your alcohol solvents
in water and in your organic solvent.
8. Present your predictions to your instructor and obtain your assigned alcohol solutes.
9. Use a set of 9 small test tubes (smallest ones in your lab tray); label them #1-#9.
10. Add 1 mL DI water to tube #1. Using a Sharpie Marker draw a horizontal line on the
tube at the meniscus of the liquid. Use this tube as a template to mark the 1 mL level on
the remaining tubes.
Aqueous Solubility of Alcohols
11. Fill tubes #2 - #5 to the mark with distilled water.
12. Begin with test tube #1
 Add one drop of the first alcohol.
 Agitate the tube and contents using the technique explained in the lab. Observe what
happens.
 Continue to add the alcohol, 1 drop at a time, followed by agitation, noting what
happens, until you have added a total of 10 drops.
 Record, in your results table, the number of drops added when you first observed
cloudiness in the mixture after agitation and observe what happens when subsequent
drops are added. If cloudiness is not observed record 10 drops for the mixture.
13. Repeat the process with the remaining alcohols in your set in test tubes #2, #3 & #4.
Solubility of Organic Solvent in Water
14. Use test tube #5, which contains 1 mL water to repeat the process to test the solubility of
your group’s assigned organic solvent in water. Record your solubility results and your
observations in your aqueous solubility table.
Solubility of Alcohols in Organic Solvent
15. Fill test tubes #6 - #9 to the 1 mL mark with your group’s assigned organic solvent and
cork them.
16. Identify your organic solvent in your procedure.
17. Test the solubilities of each of your assigned alcohols using the organic solvent in tubes
#6, #7, #8, #9 following the procedure used for testing solubility in water. (Step 12.)
18. Keep the corks on these tubes when they are not being used.
19. Keep all 9 mixtures for possible reference until all analyses and discussions are
complete.
20. Create a Table of Compounds for your assigned alcohol solutes, your group organic
solvent and water; include the bondline structure, molecular weight, densities and boiling
point of each compound. Your table belongs on the second left-hand page of your
notebook for this experiment opposite your waste disposal instructions.
Individual Data Analysis
21. Analyze your solubility data and record all observations, conclusions and explanations in
your results section.
a. Do you recognize any trends in your data? Include your specific description of any
observed trends or explanation of why you believe that there were no observable
trends.
b. Do your data support your group’s initial predictions? Explain why or why not? If
they don’t, what new insights did you gain from your analysis of the results?
Group Data Analysis
22. Group recorder: Enter all group member solubility data into a group spread sheet file on
the group laptop, change the file name to the group name, save the file to the server and
Solubility
4
CHEM 211 Experiment 4
print 8 copies of the data for each group member and the inter-group collaborators. (See
step 25) Place your group data sheets in your data binder. All Group data will be posted
on the course website at the end of the week.
23. Compare your data with that of group mates and record all observations, conclusions and
explanations in your Results section.
a. Are the trends or lack of trends in all individual data sets consistent with each other?
Explain using specific examples to illustrate your reasoning.
b. Does the entire group data set support your group’s initial predictions? Explain why
or why not? If it doesn’t, what new insights did you gain from your analysis of the
results?
c. Use the entire group data set to develop a hypothesis to explain solubility behavior of
the alcohols in water and organic solvents. Explain how your data supports your
hypothesis. Use specific examples from your data to illustrate your reasoning.
Inter-group Data Analysis
25. The group presenter obtains data sheets from another group, which used a different
organic solvent.
26. Place the inter-group collaborator data in your data binder.
27. Compare your data with that of the inter-group collaborators’ and record all observations,
conclusions and explanations in your results section.
a. Rationalize the inter-group collaborators’ data on alcohol solubility in water vs. their
organic solvent using your group’s hypothesis on alcohol solubility.
b. What additional insights does this new data set provide? Explain.
c. Reconsider your solubility hypothesis and make a clear statement of your final
proposal. Explain how it can rationalize the data from both groups.
Post Lab Data Analysis
28. Your group will be assigned one of the following sets (1-butanol and 2-butanol;
1-pentanol and 2-pentanol; 2-methyl-1-propanol and 2-methyl-2-propanol; 2-methyl-2butanol and 3-methyl-1-butanol). In collaboration with your group, compare the
solubilities of your assigned pair of compounds (from pooled data available on the course
website) in water and in all organic solvents. Use your final solubility hypothesis to
explain any differences observed. Be ready to present your explanations in the Tuesday
AM Lab discussion period.
Table 1: Solvents
Name
Molecular
Formula
Bondline Structure
Waste
Disposal
Category
Water
H2O
6
Hexane
C6H14
4
Octane
C8H18
4
Decane
C10H22
4
Dodecane
C12H26
4
Solubility
5
Table 2: Alcohol Solutes
Bondline Structure
CHEM 211 Experiment 4
Name
Molecular
formula
Waste Disposal
Category
Methanol
CH4O
6
Ethanol
C2H6O
6
1-Propanol
C3H8O
6
2-Propanol
C3H8O
6
1-Butanol
C4H10O
6
2-Butanol
C4H10O
6
1-Pentanol
C5H12O
4
2-pentanol
C5H12O
4
1-hexanol
C6H14O
4
2-hexanol
C6H14O
4
2-Methyl-1-propanol
C6H14O
4
2-methyl-2-propanol
C4H10O
4
2-methyl-2-butanol
C5H12O
4
3-Methyl-1-butanol
C5H12O
4
1,2-ethanediol
C2H6O2
4
1,2,3-propanetriol
C3H8O3
4
Solubility
6
Table 3: Aqueous Solubility
Solute
Solubility* in H2O
Alcohol 1
Alcohol 2
Alcohol 3
Alcohol 4
Organic
Solvent
*
Observations
the number of drops of solute required to produce a cloudy mixture in 1 mL of solvent.
Table 4: Solubility in Organic Solvent
Solute
Solubility* in
Solvent
Alcohol 1
Alcohol 2
Alcohol 3
Alcohol 4
*
CHEM 211 Experiment 4
Observations
The number of drops of solute required to produce a cloudy mixture in 1 mL of solvent.
 Identify
your organic solvent in the table header.