1. Water Chemistry and Acid/Base Review

2. Hydrogen bond H O H  –  +  –  +  –  +  –  + —— —— Fig. 3-2
Figure 3.2 Hydrogen bonds between water molecules
 –
 +

3. 2. 1. 3. Name 3 properties of water illustrated in this picture.
Fig. 3-3 2.
This slide
shows 3 properties
of water: Cohesion (1),
Adhesion (2), and
Capillary Action (3)
Water-conducting
cells 3.
Capillary action
Involves 1 and 2.
Direction
of water
movement 1.
Figure 3.3 Water transport in plants
150 µm
Name 3 properties of water
illustrated in this picture.

4. Fig. 3-4
Surface tension:
The measure of how hard it is to break the surface of a liquid. This property is related to cohesion.
Figure 3.4 Walking on water

5. Hydrogen bonds are stable Liquid water
Fig. 3-6
Hydrogen
bond
Ice
Hydrogen bonds are stable
Liquid water
Hydrogen bonds break and re-form
Figure 3.6 Ice: crystalline structure and floating barrier

6. The Solvent of Life
A solution is a liquid that is a homogeneous mixture of substances
A solvent is the dissolving agent of a solution
The solute is the substance that is dissolved
An aqueous solution is one in which water is the solvent
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7. – – – – – – – – – – – + + + + + + + + + +
Fig. 3-7
Note how the water molecules turn
themselves so that the opposite charged
part of the water is facing the ion. Water
is pulling the sodium ion from the chloride
ion and breaking the ionic bond.
Salt will then dissolve. – Na + + + – – + – – Na + – + +
Cl–
Cl– + – – + – + –
Figure 3.7 Table salt dissolving in water –

8. 2H2O Hydronium Hydroxide ion (H3O+) ion (OH–)
Fig. 3-UN2
Water “tugs” on other water molecules. Sometimes one water may pull a hydrogen proton away from another water
The hydrogen proton
Pulled away left behind its
electron. We now have
hydroxide (OH-). H H O H O O H O H H H H
2H2O
Hydronium
ion (H3O+)
Hydroxide
ion (OH–)
“Mutilated”
Mouse – missing
an “ear” or hydrogen
proton. What to
remember: this
solution has more OH-
ions than H+ ions.
Solution is basic: pH
greater than 7.
Hydronium = “Mutated Mouse”
- It has 3 “ears”. What to
remember: a solution in this state
would have more H+ ions than OH- ions
and would be acidic with a pH less than 7.

9. Acids and Bases
An acid is any substance that increases the H+ concentration of a solution
A base is any substance that reduces the H+ concentration of a solution (therefore bases have more OH- ions in the solution)
pH means potential hydrogen.
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10. Acidic solutions have pH values less than 7
Basic solutions have pH values greater than 7
Most biological fluids have pH values in the range of 6 to 8
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11. Figure 3.9 The pH scale and pH values of some aqueous solutions1
Battery acid
Gastric juice,
lemon juice 2 H+ H+ H+ H+
OH– 3
Vinegar, beer,
wine, cola
OH– H+ H+
Increasingly Acidic
[H+] > [OH–] H+ H+ 4
Acidic
solution
Tomato juice
Black coffee 5
Rainwater 6
Urine
OH–
Saliva
OH–
Neutral
[H+] = [OH–] H+ H+
OH– 7
Pure water
OH–
OH– H+
Human blood, tears H+ H+ 8
Seawater
Neutral
solution 9
Figure 3.9 The pH scale and pH values of some aqueous solutions 10
Increasingly Basic
[H+] < [OH–]
Milk of magnesia
OH–
OH– 11
OH– H+
OH–
OH–
Household ammonia
OH– H+
OH– 12
Basic
solution
Household
bleach 13
Oven cleaner 14

12. Buffers The internal pH of most living cells must remain close to pH 7
Buffers are substances that minimize changes in concentrations of H+ and OH– in a solution
Carbonic acid
Bicarbonate ion
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings