1. General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 8
Solutions
8.1 Solutions
Lectures
© 2013 Pearson Education, Inc.

2. Solutions: Solute and Solvent
are homogeneous mixtures of two or more substances.
contain a solute that is uniformly dispersed in another substance called the solvent.

3. Nature of Solutes in Solutions
are spread uniformly throughout the solvent.
are not visible, but can give a color to the solution.
are usually present in a smaller amount than the solvent.

4. Examples of Solutions
The solute and solvent in a solution can be a solid, liquid,
and/or a gas.

5. Learning Check Identify the solute in each of the following solutions.
1. 2 g sugar and 100 mL water
mL of ethyl alcohol and 30.0 mL of
methyl alcohol
mL water and 1.50 g NaCl
4. air: 200 mL O2 and 800 mL N2

6. Solution Identify the solute in each of the following solutions.
1. 2 g sugar and 100 mL water sugar
mL of ethyl alcohol and
30.0 mL of methyl alcohol methyl alcohol
mL water and 1.50 g NaCl NaCl
4. air: 200 mL O2 and 800 mL N2 O2

7. Water Water is the most common solvent in nature. is a polar molecule.
forms hydrogen bonds between the partially positive hydrogen atom in one molecule and the partially negatively charged oxygen atom in a different water molecule.

8. Water in the body The average adult body contains 60% water by mass.
Dehydration occurs when as little as 10% of body fluids are lost.
Water lost can be replaced by liquids and foods in the diet.

9. Formation of a Solution
To form a solution, the solute and solvent must have like polarities.
The energy between the solute and solvent particles must be strong enough to overcome the initial attractive forces between the solvent molecules and solute particles.

10. Solutions with Ionic and Polar Solutes
Na+ and Cl– ions
on the surface of a NaCl crystal are attracted to polar water molecules.
are hydrated in solution by many H2O molecules surrounding each ion.

11. Equations for Solution Formation
When NaCl(s) dissolves in water, the reaction can be
written as:

12. Learning Check Solid LiCl dissolves in water because:
A. The Li+ ions are attracted to the oxygen atom () of water.
B. The Li+ ions are attracted to the hydrogen atom ( +) of water.
C. The Cl– ions are attracted to the oxygen atom () of water.
D. The Cl– ions are attracted to the hydrogen atom ( +) of water.
E. both A and D
F. both B and C

13. Solution Solid LiCl dissolves in water because:
A. The Li+ ions are attracted to the oxygen atom () of water.
D. The Cl– ions are attracted to the hydrogen atom ( +) of water.
E. both A and D

14. Water and a Polar Solute
Molecules of polar covalent compound methanol, CH3OH, form hydrogen bonds with polar water molecules to form a methanol–water solution.

15. Like Dissolves Like Two substances form a solution when
there is an attraction between the particles of the solute and solvent.
a polar solvent, such as water, dissolves polar solutes, such as sugar and/or ionic solutes, such as NaCl.
a nonpolar solvent, such as hexane (C6H14) dissolves nonpolar solutes, such as oil or grease.

16. Like Dissolves Like Solvents Solutes Water (polar) Ni(NO3)2
CH2Cl2 (nonpolar) (polar)
I2 (nonpolar)

17. Learning Check
Will each of the following solutes dissolve in water? Why
or why not?
A. Na2SO4
B. gasoline (nonpolar)
C. I2
D. HCl

18. Solution Will each of the following solutes dissolve in water? Why
or why not?
A. Na2SO Yes, the solute is ionic.
B. gasoline No, the solute is nonpolar.
C. I2 No, the solute is nonpolar.
D. HCl Yes, the solute is polar.
Most polar and ionic solutes dissolve in water because
water is a polar solvent.