Physical Properties - Solubility
Essential Standard 6.P.2: Understand the structure, classifications and physical properties of
matter.
Clarifying Objective 6.P.2.3: Compare the physical properties of pure substances that are
independent of the amount of matter present including density, melting point, boiling point and
solubility to properties that are dependent on the amount of matter present to include volume,
mass and weight.
Learning Goal: By able to identify the solvent and solute in a solution and
determine what factors affect solubility.
Mini-Lesson #3:
Copy each statement and fill in the blanks with the correct words.
1. The melting point of a substance is the temperature at which it changes
from a ________ to a liquid.
2. The boiling point is __________ for each different substance.
3. There are _______ degrees of difference between water’s melting and
boiling points.
Engage (whole class):
Review “mixtures” and “solutions”. Recall that a solution is a special type of
mixture. Now we will learn about the parts of a solution and how well different
substances dissolve into one another.
Active Learning (small group):
With your group, conduct the solubility investigation using the materials provided.
Complete one data sheet per group.
Reflection (small group and individual):
Answer the discussion questions on your lab sheet.
Fill in the “Own Words” definitions for solubility, solvent, and solute on your
vocabulary list.
Homework:
None! (Continue planning Unit Project)
Group #_________ Core _________
Solubility Lab Investigation
Purpose: The solubility of a liquid describes how easy it is for another substance
to dissolve in the liquid. If you dissolve a solid in a liquid, the solid is called the
solute and the liquid is called the solvent. In this lab, you will conduct an
experiment to test the solubility of three solvents (water, vinegar, and rubbing
alcohol) using three solutes (salt, sugar, and cornstarch).
Materials:
Solvents: water, rubbing alcohol, vinegar
Solutes: sugar, cornstarch, salt
Other materials: chemplates, droppers, craft sticks, toothpicks
Procedure:
1) Use one dropper to transfer a small amount of water from the cup to three
different wells of the chemplate.
2) Use a different dropper to transfer a small amount of rubbing alcohol to
three different wells of the chemplate.
3) Use the last dropper to transfer a small amount of vinegar to three
different wells of the chemplate.
4) Use a craft stick to transfer a small amount of sugar to one of the water
wells, one of the rubbing alcohol wells, and one of the vinegar wells, without
touching the stick to any of the liquids.
5) Use a toothpick to stir each mixture, observing whether the sugar dissolves
into any of the solvents. (Use a clean toothpick for each mixture.)
6) On the data table, indicate whether each mixture dissolved or did not
dissolve by writing “yes” or “no” in each row.
7) Repeat steps 4-6 for corn starch, and then for salt. Make sure that each
well only contains one solvent and one solute, and that you are not using the
same utensils in different substances.
Data:
Record your data as “yes” or “no” in each space to indicate whether the solute
dissolved into the solvent
Solvent Solute
Sugar
Corn Starch
Salt
Water
Rubbing Alcohol
Vinegar
Discussion Questions:
1) Two students dissolve a spoonful of salt into a container of water. Which
substance is the solvent and which is the solute?
2) Chocolate powder is soluble in milk. What does soluble mean?
3) With the three solutes tested in the solubility lab, which liquid was the
worst solvent (water, rubbing alcohol, or vinegar)? Explain your reasoning.
4) With the three solutes tested in the solubility lab, which liquid was the best
solvent (water, rubbing alcohol, or vinegar)? Explain your reasoning.
5) What else could you do (besides just stirring) to make a solute dissolve into
a solvent?
6) Does the amount of solute and solvent seem to affect whether or not it
dissolves?