Chapter 15 - Water and Aqueous Systems

Question 0

What distinguishes a colloid from a suspension and a solution?

Answer 0

Colloids have particles smaller than those in suspensions and larger than those in solutions.

Question 1

How does a suspension differ from a solution?

Answer 1

• Particles of a suspension are much larger

- They do not stay suspended indefinitely

Question 2

How can you determine through observation that a mixture is suspension?

Answer 2

At least two substances can be clearly identified.

Question 3

What types of substances dissolve most readily in water?

Answer 3

• Polar covalent bonds (electrolytes)

- Ionic compounds

Question 4

What property of all ionic compounds make them electrolytes?

Answer 4

The ability to dissociate in ions. Water will solvate them because they are charged.

Question 5

Identify the solvent and the solute in vinegar, a dilute aqueous solution of acetic acid.

Answer 5

Solvent -> aqueous solution, H2O

Solute -> acetic acid

Question 6

Which of the following dissolve to a significant extent in water?

a. CH4
b. KCl
c. I2
d. MgSO4
e. Sucrose (C12H22O11)
f. NaHCO3

Answer 6

a. ❌ (non-polar)
b. ✔️ (polar)
c. ❌ (non-polar)
d. Ok–✔️
e. ❌ (sugar is polar, not a strong electrolyte)
d. ✔️

Question 7

What causes the high surface tension, low vapor pressure, and high boiling point of water?

Answer 7

Hydrogen bonding

Question 8

How are water molecules arranged in ice?

Answer 8

In a hexagonal arrangement.

Question 9

Why does water form spherical drops on some surfaces?

Answer 9

Water molecules at the surface of the water drop cannot form hydrogen bonds with the molecules in air, so they are drawn into the body of the liquid.

Question 10

What effect does a surfactant have on the surface tension of water?

Answer 10

It interferes with the hydrogen bonding. Reduces surface tension which causes beads of water to collapse and spread out.

Question 11

What is the difference between a strong electrolyte and a weak electrolyte?

Answer 11

▪️Strong electrolytes: all or nearly all of the solute exists as ions.
▪️Weak electrolytes: only a fraction of the solute in the solution exists as ions.

Question 12

How do properties of colloids differ from those of suspensions and solutions?

Answer 12

▪️Colloids are cloudy☁️ or milky

Question 13

List examples of colloids.

Answer 13

▫️whipped cream
▫️marshmallow
▫️milk, mayonnaise
▫️fog, aerosol
▫️dust in air
▫️jelly, paint, and blood.