8. 8
pH
pH = – log [H+]
Log scale means 10X
change per unit!
[H+]= 10-1
M
[H+]= 10-9
M
9. 9
Buffers
•Buffers resist changes to the pH of a
solution when H+
or OH-
is added to the
solution.
•Buffers accept hydrogen ions from the
solution when they are in excess and donate
hydrogen ions when they have been
depleted.
10. 10
Overall lessons:
• Many properties of water are emergent properties due to hydrogen
bonding.
• The cohesion of water molecules to each other is exploited by plants
and animals.
• Water resists temperature changes by absorbing lots of heat.
• Lower density of ice causes it to float & insulate the water below.
• The polarity of water allows it to dissolve other polar molecules.
• Non-polar compounds are hydrophobic and not easily dissolved in
water.
• A mole of a compound has a constant # of molecules.
• Adding or removing hydrogen ions changes the pH of a solution.
• Buffers resist pH changes by accepting or donating H ions when
[H+] changes.
