______________________________________________________________________________
Solubility Lab
A. Objective: To determine the solubility of the following solvents: water, rubbing alcohol, oil. You will
have the following solutes to conduct this experiment: sugar, salt, and cornstarch. Solubility means the
ability to dissolve a substance.
B. Pre-Lab: (see board for instructions)
Solute
A substance (usually solid) that is dissolved in another substance. (Ex; Salt)
Solvent
Substances (usually liquid) capable of dissolving another substance. (Ex: Water)
Soluble
Capable of being dissolved in a solvent.
Partially soluble Part of a solute dissolves leaving the other part non-dissolved and still visible.
Insoluble
C.
1.
2.
3.
4.
5.
The inability of a substance to be dissolved.
Safety Rules:
Stay with group.
Wear goggles.
NO HORSEPLAY. Horseplay will result in ending the lab. You will do book work.
Keep work area clean! Always clean up completely at the end of the lab.
Do NOT leave until the teachers has checked off your lab station and supplies.
D. Materials: Below is a list of materials for the lab. In the Procedure Section below, describe how you
will use these materials to complete the lab objective.
Solvents:
Solutes:
Cups:
Other materials:
water, rubbing alcohol, oil
sugar, cornstarch, salt
120 mL cups (3) each labeled a solvent, 40 mL cups (3) each labeled
cups for solvents, spoons (3), stirrers (3), markers (1)
E. Lab responsibilities:
1. Odd-numbered seats are team captains and responsible that everybody is on task.
2. Even-numbered seats are materials and clean-up. They are responsible for keeping clean.
F. Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Obtain materials.
Add 120 mL of each solvent into the 120 mL cup. This is your SUPPLY cup!
Pour 40 mL of alcohol, oil, and water in each 40 mL cup (FROM THE SUPPLY CUP!). This is your TESTING cup!
Put the same amount solute in EACH cup. Start with SALT!
Amount of solute: ________________________.
Stir the salt into the solvent and observe if it is dissolved and how well it is dissolved. (After stirring, let it “settle” to see if it
really dissolved or if it was just suspended in the solution. Suspended in the solution is not dissolving.)
Record the information on your chart.
Pour out each cup down the drain and rinse.
Repeat steps 3-8 with the other solutes: sugar and cornstarch.
Page 1 of 3
Why Follow the Water?
______________________________________________________________________________
10. CLEAN and DRY EACH CUP OUT thoroughly before returning it to supply box.
11. Analyze the results in the chart and answer the questions below:
G.
Data
Solvent
Water
Oil
Alcohol
Water
Oil
Alcohol
Water
Oil
Alcohol
H.
1.
Solute
Observations (soluble, insoluble, partially
soluble)
Optional: How
many until it was
saturated?
Salt
Salt
Salt
Sugar
Sugar
Sugar
Cornstarch
Cornstarch
Cornstarch
Analysis:
Rank all the solvents (liquids) from best to worst by how well they were able to dissolve the substances. (This is the
analysis of your results. Discuss the chart thoroughly. 3-4 sentences.)
2.
Explain what solutes dissolved in what solvent.
3.
A. What type of property is solubility? (Physical or chemical) B. Explain what solubility is.
4.
What is the difference between a solvent and a solute? What solvents did you use? What solutes did you use?
5.
Explain how this data might be useful or applied to real life?
6.
Conclusion: Name 2 things that you learned from this lab. (“I learned that…” full sentences!!)
Page 2 of 3
Why Follow the Water?
______________________________________________________________________________
WHY FOLLOW THE WATER?
Post-Lab Questions (Answer Key)
Ease of Evaporation
1) Based on your discussion about ease of evaporation, rank water, oil, and alcohol from the easiest to
evaporate to the hardest to evaporate.
Rubbing alcohol is the easiest to evaporate, water is next, and vegetable oil is the hardest to evaporate.
2) Based upon the results regarding evaporation ALONE, which liquid would you expect to be the most useful
for life? Explain your reasoning.
Based ONLY on the fact that vegetable oil is more stable to evaporation than water or rubbing alcohol, students might guess that
vegetable oil is the most important liquid for life. This experiment introduces the concept that we can measure and compare
properties of various substances.
Solubility Experiment
3) With the three solutes tested in the solubility lab, which liquid was the worst solvent (water, rubbing
alcohol, or vegetable oil)? Explain your reasoning.
Students will find that the vegetable oil was a worse solvent than water and rubbing alcohol for the solutes tested.
4) Sugars, salts, and other solutes need to be able to move into, out of, and inside cells in order to carry out the
basic functions of life. If a cell composed of mostly the liquid you listed in Question 3, would the cell still
be able to transport solutes easily around the cell? Explain your reasoning.
If a cell were composed of mostly oil, sugars and salts would not be easily dissolved and would therefore not be able to move
around inside the cell as easily as with a cell filled with water. The sugars and salts also would not be able to react with other
molecules because they would remain in their less active, solid state.
5) Based upon the results of the solubility experiment, rank the three liquids from highest solubility to lowest
solubility.
Students should find that water has the highest solubility, rubbing alcohol is next, and vegetable oil has the lowest solubility.
Some students may have difficulty distinguishing between the solubility of rubbing alcohol and water.
6) Based upon the results of the solubility experiment ALONE, which liquid would you expect to be the most
useful for life? Explain your reasoning.
Water is important to living things because it can be used to dissolve solids such as sugars and salts Chemical reactions can
occur more easily when these molecules are dissolved in a solvent such as water. Water can serve as a good solvent for
dissolving and transporting these molecules necessary for life.
Page 3 of 3
Why Follow the Water?