Chapter 7: Solutions
Solutions
• Mixture
– Solute is
uniformly
distributed in
the Solvent
• Water is the
most common
solvent
Hydrogen bonds
• Hydrogen bonding
– Very important interactions (not just with water)
Hydrogen bonds
• Hydrogen bonds in Biology are very important
• Example: DNA
Examples of Solutions
Solutions
• Gases form solutions easily
– Particles move rapidly
– Don’t have any attraction to
themselves anyway
• Solids and liquids:
– “like dissolves like”
– Polar solvents dissolve ionic
and polar compounds
– Nonpolar solvents dissolve
nonpolar compounds
Electrolytes
Electrolyte: solute that conducts electricity when dissolved
• Strong electrolyte:
– dissociates completely into ions in water


NaCl (s) 
 Na (aq)  Cl (aq)
H2 O
• Weak electrolyte:
– only a few molecules dissociate into ions in water
– Conduct electricity weakly
– Dissociation / recombination


HF (aq) 
 H (aq)  F (aq)
Electrolytes
• Nonelectrolytes:
– Dissolve in water as whole molecules
2O
C12H 22O11 (s) H

C12H 22O11 (aq)
Electrolytes
Equivalents
Equivalent:
amount of ion equal to 1 mole of positive or negative
electrical charge
How many moles of sodium ions are in 500. mL of blood, if
a typical concentration for Na+ in the blood is 138
mEq/L?