Particles with a Charge

Did you know that there are charged particles in your body that conduct electricity?

These charged particles are called ions.

What is an electrolyte? Electrolyte is a compound that produce solutions of ions that
conduct electricity in water (conduct an electric current)

Give an example of an electrolyte. NaCl, Acetic Acid

What is a nonelectrolyte? Nonelectrolytes are substances that do not form ions in
water and cannot conduct electricity.

Give an example of a nonelectrolyte. Organic molecules like ethyl alcohol and sucrose.

Ionic Solutions form in two ways Ionization and Dissociation
Ionization

What is ionization? Water pulls apart the molecules of neutral atoms (polar covalent

compound) forming ions.
Draw of diagram of ionization (figure 10).
HCl
Dissociation

+
H2O
H3O+ +
Cl-
What is dissociation? Ions already exist in the ionic compound. The compound is
pulled apart into positive and negative ions by the attraction of surrounding polar

water molecules.
Draw a diagram of dissociation (figure 11 and 12).
NaCl is pulled apart. Water
molecules surround and separate
the Na+ ions from the Cl- ions.
Reading check: What are the differences and similarities between dissociation and ionization? Big
difference is that ionization occurs with covalent compounds whereas dissociation occurs
with ionic compounds. With dissociation the ions already exist in the compound. Big
Similarity is that they both produce an electric current.
Effects of Solute Particles
Briefly describe each of the following effects:
Lowering Freezing Point Adding a solute like antifreeze lowers the freezing point. (The
added particles interfere with the formation of the pattern necessary for freezing.)

Animal Antifreeze Body substances, like glycoprotein, prevent ice crystals from
forming in moist tissues. (caribou-lower legs and fish)

Raising Boiling Point Solute particles interfere with the evaporation of solvent
particles. More energy is needed for the solvent to evaporate, therefore the boiling
point will be higher.

Car Radiators Solute particle block the surface making in more difficult for the
solvent to vaporize. It takes a higher temp to make the radiator boil over.
Reading check: Determine what has taken place, ionization or dissociation, if calcium phosphate Ca3(PO4)2
breaks in Ca+ and PO4. Dissociation (ionic compound)
Think about it: In the Midwest, we put salt on ice that forms on sidewalks and driveways. The salt helps
melt the ice, forming a saltwater solution. Explain why this solution may not refreeze. The salt acts like
antifreeze. The ions from the salt interfere with the pattern necessary for freezing.
When Water Won’t Work

Why is water referred to as the universal solvent? Water can dissolve many things.

Quick review: Water is polar because it has separated positive and negative areas

What is a nonpolar substance? Nonpolar materials do not have positive & negative
areas.

Does water (which is polar) attract nonpolar substances? No
Nonpolar Solutes

Figure 15: Why don’t vinegar and oil mix? Vinegar is polar and oil is nonpolar.

Is vinegar polar or nonpolar? Would it mix with water? Polar. Yes, it would mix with water.

Is oil polar or nonpolar? Would it mix with water? Nonpolar. No, it would not mix with
water.
Vaersatile Alcohol

Can a substance be both polar and nonpolar? Explain. Yes. For example, ethanol has a polar
end and a nonpolar end.
Useful Nonpolar Molecules
Drawbacks of Nonpolar Solvents

Mineral Oil is a solvent that can dissolve? Candle wax, bubble gum

Turpentine is a solvent that can dissolve? Oil-based paint

What are two drawbacks to using nonpolar solvents? They are flammable, some are toxic,
some produce harmful vapor
How soap works?

Is soap a polar or nonpolar substance? Both polar and nonpolar

How does soap work? The ionic end of soap will dissolve in water and the
hydrocarbon portion (nonpolar side) will dissolve in oils and dirt. The
hydrocarbon side removes the dirt/oil and then the water will wash it away.
The nonpolar end will
dissolve the oil/dirt
Soap has a polar end
and a nonpolar end.
and the polar end
will be attracted to
the water (wash it away)
Reading Check: Why doesn’t water alone clean oily dirt? Water is polar and can’t dissolve oil and
dirt because they are nonpolar substances.
Polarity and Vitamins

Are vitamins polar or nonpolar compounds?
Depends on the vitamin. Vitamin A is nonpolar, Vitamins B & C are polar
Reading check: Explain the phrase “like dissolves like” and give an example of two polar “like” substances.
Polar substance can mix/dissolve other polar substances and nonpolar can mix/dissolve
other nonpolar. Examples: salt and water are both polar (salt will dissolve in the water
to form a salt water solution); mineral oil and candle wax are both nonpolar
Think about it: What might happen to your skin if you washed with soap too often? Because soap
dissolves oil, washing with soap too often can strip your skin of natural oils.