1. Chapter 12 Solutions 12.1 Solutions
Learning Goal Identify the solute and solvent in a solution; describe the formation of a solution.
© 2014 Pearson Education, Inc.

2. Calculating a Percentage (1.4C) Interpreting a Line Graph (1.4E)
Chapter 12 Readiness
Key Math Skills
Calculating a Percentage (1.4C)
Interpreting a Line Graph (1.4E)
Core Chemistry Skills
Writing Conversion Factors from Equalities (2.6)
Using Conversion Factors (2.7)
Identifying Attractive Forces (10.4)
Using the Ideal Gas Law (11.8)
© 2014 Pearson Education, Inc.

3. Solutions
Solutions
are homogeneous mixtures of two or more substances
contain a solute, usually in smaller quantity, and uniformly dispersed in another substance called the solvent, usually present in greater quantity

4. Solutes
Solutes are not visible and
cannot be separated by filtration
can be separated by evaporation
can give color to a solution

5. Types of Solutes and Solvents
The solutes and solvents in solutions can be
solids, liquids, or gases.

6. Water as a Solvent
Water, the most common solvent,
is a polar molecule
forms hydrogen bonds between molecules

7. Formation of a Solution
Na+ and Cl ions
on the surface of a NaCl crystal are attracted to polar water molecules
in solution are hydrated by H2O molecules that surround each ion

8. Solute – Solvent Attractions
Attractive forces occur between solute and solvent particles when the solute and solvent are similar in polarity.
The expression “like dissolves like” describes the common polarities of the solute and solvent particles needed to form a solution.

9. Solute – Solvent Attractions
Like dissolves like. In each test tube, the lower layer is Ch2Cl2 (more dense), and the upper layer is water (less dense).
(a) Ch2Cl2 is nonpolar and water is polar; the two layers do not mix. (b) The nonpolar solute I2 (purple) is soluble in the nonpolar solvent Ch2Cl2. (c) The ionic solute Ni (No3)2 (green) is soluble in the polar solvent water.

10. Solute – Solvent Attractions

11. Solutions, Ionic Solutes
In water, a polar solvent, the hydrogen bonds provide strong solvent–solvent attractions.
When NaCl crystals are placed in water,
partially negative oxygen atoms in water molecules attract positive Na+ ions
partially positive hydrogen atoms in other water molecules attract negative Cl− ions

12. Solutions, Ionic Solutes
When NaCl(s) dissolves in water, the formation of the solution can be written as
NaCl(s) Na+(aq) + Cl−(aq)
solid separation of ions
H2O

13. Solutions, Polar Solutes
Polar molecules such as CH3—OH are soluble because of the polar –OH group that forms hydrogen bonds with the polar solvent water.

14. Solutions, Nonpolar Solutes
Solutes that are nonpolar, such as iodine (I2), oil, or grease, do not dissolve in the polar solvent water.
There are no attractions between the nonpolar solute particles and the polar solvent.
Nonpolar molecules will form a solution with nonpolar solvents.

15. Learning Check
Solid LiCl is added to water. It dissolves because
the Li+ ions are attracted to the
1) oxygen atom ( –) of water
2) hydrogen atom ( +) of water
B. the Cl ions are attracted to the

16. Solution
Solid LiCl is added to water. It dissolves because
A. the Li+ ions are attracted to the
1) oxygen atom ( –) of water
the Cl ions are attracted to the
2) hydrogen atom ( +) of water

17. Learning Check
Will the following solutes dissolve in water?
A. Na2SO4
B. gasoline (nonpolar)
C. I2
D. HCl

18. Solution
Will the following solutes dissolve in water?
Na2SO4 Yes, the solute is ionic.
gasoline (nonpolar) No, the solute is nonpolar.
I2 No, the solute is nonpolar.
HCl Yes, the solute is polar.
Most polar and ionic solutes dissolve in water because water is a polar solvent.