CHEM121 Lecture Ch7(part1)
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Transcript CHEM121 Lecture Ch7(part1)
Chapter 8: 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?