Answer Key

ANSWER KEY
Part I- The Basics:
1. Define the following terms:
a. Solute – substance being dissolved
(lower concentration)
Worksheet – Introduction to Solutions
c. Solution – homogenous mixture of 2 or
more substances (solute + solvent)
b. Solvent – substance doing the
dissolving (higher concentration)
d. Dissolution – the process of dissolving
2. Identify the solute & solvent in each:
a) Kool- aid b) ocean water c) your blood
Kool-aid = solute Salt = solute Blood cells & nutrients = solute
Water = solvent Water = solvent Water = solvent
3. Water is polar. Draw a picture of a polar water molecule with the charges & explain what this means.
The oxygen atom in water is more electronegative & hogs the electrons, giving it a partial neg. charge. This
leaves the hydrogen atoms with a partial pos. charge. (See #6 for picture)
4. Explain why H 2 O’s polarity makes it such a great solvent? (In terms of bonding, what 2 types of substances
are soluble in water?)
Water is polar and readily forms hydrogen-bonds with other polar substances. It will readily dissolve polar
and ionic solutes.
5. Give a common example of something that is insoluble in water & explain why it is not soluble.
Oil is insoluble in water because it is nonpolar.
6. Starting with the images below, show how each of the starting substances would dissolve in a cup of water.
Use as many water molecules as needed.
Substances before dissolution:
Substances after dissolution:

7. The way NaCl and glucose dissolve in water is different from each other. Explain how & why.
Glucose molecules (covalent) remain intact when dissolved in water. Each glucose molecule is surrounded by
water molecules and forms hydrogen bonds with these water molecules.
Salt compounds (ionic) dissociate in water. This means that the cations and anions separate. Each ion is
surrounded by water molecules.
8. a) Define the term dissociation.
Dissociation - The separation of cations and anions in solution
b) What types of compounds undergo dissociation during the dissolving process?
Ionic compounds undergo dissociation during the dissolving process.
9. How do you know when something is dissolved?
Something is dissolved when you can no longer see it separately in the solution.
10. a) Do solids dissolve in water? Give examples.
Some solids dissolve in water, such as sugar and salt.
b) Do liquids dissolve in water? Give examples.
Some liquids dissolve in water, such as alcohol.
c) Do gases dissolve in water? Give examples.
Gases can dissolve in water if they are put under pressure. Ex: CO 2
11. Does dissolving always involve water? Explain.
No, other substances can also be solvents, such as gasoline, hexane, etc.
12. What does the saying “like dissolves like” mean in chemistry?
Polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.
Part II- Real World Applications:
1. A swim meet will not be cancelled due to rain, but it will be cancelled due to lightning. Explain.
Water in the pool is not pure and contains many substances (such as salt from your body) that are
electrolytes (will conduct an electrical current). If lightening strikes the pool, anyone in it would be
electrocuted.
2. Soap is able to dissolve and thus remove things like grease (non-polar) and sugar (polar). Do you think soap
is polar, nonpolar, or both? Explain.
Soap is both polar and nonpolar. The nonpolar regions of soap molecules surround things like grease
(nonpolar) and the polar regions surround things like sugar (polar). Once these molecules are surrounded,
they can be removed.
3. Sharpie pens do not rub off in water. Do you think sharpie pen ink is polar or nonpolar? How could you
remove sharpie pen?
Sharpie pens are nonpolar since they do not dissolve in polar water.
4. Auto mechanics will often use gasoline to clean grease off of their hands. Explain.
Gasoline is a nonpolar solvent that will easily dissolve the nonpolar grease.
Part III- Reading Questions: Read the article “Why Solubility Matters” and answer the following questions.
1. a) What is the importance of vitamins in your body?
Vitamins catalyze (speed up) the chemical reactions that occur in your body to keep you alive and
healthy.

) What is the importance of minerals in your body?
Minerals help promote certain chemical reactions or form structures in the body.
2. What does the saying “like dissolves like” mean?
Polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.
3. a) How does your body absorb and store water soluble vitamins?
Water soluble vitamins are dissolved in water when ingested, and then go into the blood stream to be used
immediately.
b) How is this different for fat soluble vitamins?
Fat soluble vitamins are dissolved in the fats from food and stored in body tissues for future use.
4. Why is it necessary to consume moderate amounts of fat in a healthy diet?
These fats are essential for the proper absorption of fat-soluble vitamins.
5. Are people more likely to become deficit in water soluble vitamins or fat soluble vitamins? Explain your
reasoning.
People are more likely to become deficit in water soluble vitamins because these are not stored in the body.