Water Basics• Polar: part of a molecule is
slightly positive, while another part is slightly negative
• Oxygen “hogs” electrons from hydrogen– 8 protons: 10 electrons– Negative charge
• Hydrogen– 1 proton: 0 electrons– Positive charge
• Creates hydrogen bonds where one water sticks to another
1
1
1
2
4
3
2
1
6
5
1
1
+ +
-
Red = Oxygen (negative) White = Hydrogen (positive)
+ + + +
+
+ +
+ + +
+ +
+ +
+
+++
+ +
+ +
+
+ +
+
+
++
+ +++
+
+ +
++
+ + +
+ +
+ +
+ +
+++++++
- - -
- -
----
-
- -
-
- - - - -
----
- - - -
Water Properties• High specific heat:
Resists temp changes– Much energy needed
to break water bonds– Helps to maintain a
constant body temp• Cohesion: polar water
molecules attracted to other polar water molecules
• Adhesion: polar water sticks to other moleculesWhy can this insect walk on water?
It is not heavy enough to break the bonds that hold the water molecules together.
7ml
6.8ml
Solutions• Solution: mixture where 1
substance dissolves in another
• 2 parts to a solution1) Solute: substance that
dissolves• Atoms, ions, molecules
2) Solvent: substance in which the solute is dissolved• Usually waterSUGAR
KOOL AID
Solution
Solutions• Solution: mixture where 1
substance dissolves in another
• 2 parts to a solution1) Solute: substance that
dissolves• Atoms, ions, molecules
2) Solvent: substance in which the solute is dissolved• Usually water
Ex: Human blood– Solvent: Plasma (watery
part of blood) – Solutes: Carbs, proteins,
sugars, etc…
• pH scale measures the amount of H+ ions in a solution• 1 minute: Discuss with your neighbor:
A) Which base has the most H+ ions?B) Which substance has the fewest H+ ions?C) Which is the strongest acid?
pH ScaleAcid Base
neutralMore OH-
More H+ Few H+Few OH-
LemonsMilk
AmmoniaSoft drink
BloodBaking soda
blood
Ammonia
Lemons
• pH scale measures the amount of H+ ions
• Some molecules release H+ ions when dissolved
• H+ ions accumulate (acids)
pH Scale
H+
H+H+H+H+H+
H+H+ H+
Substance A
Acidic Solution
• pH scale measures the amount of H+ (hydrogen) ions
• Some molecules release H+ ions when dissolved
• H+ ions accumulate (acids)
• Some molecules release OH- (hydroxide) ions when dissolved
• OH- ions accumulate (bases)
pH Scale
OH-
OH-OH-OH-
OH-
OH-
OH- OH- OH-Substance B
Basic (alkaline) Solution
• pH scale measures the amount of H+ ions• Some molecules release H+ ions when dissolved
• H+ ions accumulate (acids)• Some molecules release OH- ions when dissolved
• OH- ions accumulate (bases)• pH balance vital to life
– Ex: Blood pH (7.4): Proteins break down outside normal pH
pH Scale
• Normally: Balance of H+ and OH- ions in blood (7.4 pH)
• Alcohol abuse: Excess alcohol lowers blood pH (H+ ions accumulate)
• Kidney removes excess H+• Can lead to kidney damage
Blood pH
H+
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
OH-
H+
H+H+
H+
H+H+H+
H+ H+
H+
H+
H+
H+
H+
H+
H+H+
H+
H+
Review1) Vocabulary: Polar, Adhesion, Cohesion, High Specific Heat, Solution,
Solute, Solvent, pH 2) Name 4 basic features of water.3) Which water property explains that one atom is positively charged,
while another is negatively charged?4) How does cohension and adhesion differ?5) Which is a stronger acid? Substance A with a pH of 5 or substance B
with a pH of 3?6) Which has more H+ ions? Substance A with a pH of 5 or substance B
with a pH of 3?7) Which has more OH- ions? Substance A with a pH of 5 or substance B
with a pH of 3?8) How does a solute differ from a solvent?9) What is the solute and solvent of blood?