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CH. 2-2 IN CLASS NOTES
PROPERTIES OF WATER
Water, Water Everywhere
If you have ever seen a photograph of Earth from space, you know that much of the planet is covered by water. Water makes life on Earth possible. If life as we know it exists on some other planet, water must be present to support that life.
Section 2-2
Interest Grabber
Go to Section:
1. THE WATER MOLECULEH2O
NEUTRAL-10 P & 10E
BENT SHAPE P. 40
2. WATER IS A POLAR MOLECULE
O-SLIGHT NEG. CHARGEH-SLIGHT POS. CHARGEMOLECULES IN WHICH THE
CHARGES ARE UNEVENLY DISTRIBUTED
LIKE A MAGNET W/ POLES---=_____ & += BETWEEN_____
3. HYDROGEN BONDS--------
NOT AS STRONG AS IONIC OR COVALENT(STRONGEST)
POLAR MOLECULES ATTRACT EACH OTHER—BECAUSE PARTIAL + / -
4. PROPERTIES OF WATER
A. SINGLE MOLECULE MAY HAVE 4 H-BONDS AT THE SAME TIME
B. COHESION-ATTRACTION BETWEEN MOLECULES OF THE SAME SUBSTANCE
EX. WATER BEADS
C. ADHESION
ATTRACTION BETWEEN MOLECULES OF DIFFERENT SUBSTANCES
EX: READING A GRAD. CYL.; CAPILLARY ACTION IN PLANTS
ADHESION BETWEEN WATER & GLASS IS STRONGER THAN WATER VS. WATER
D. MIXTURE
2 OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXED
EX: SALT/PEP. STIRREDEARTH’S ATMOSPHERE
E. 2 TYPES OF MIXTURES WITH WATER
1. SOLUTIONS-all the compounds are evenly distributed throughout
a. solute-substance dissolved (salt)b. solvent-substance in which the
solute is dissolved (water)
Cl-
Water
Cl-
Na+
Water
Na+
Section 2-2
Figure 2-9 NaCI Solution
Go to Section:
Section 2-2
Figure 2-9 NaCI Solution
Go to Section:
Cl-
Water
Cl-
Na+
Water
Na+
2. SUSPENSIONS
Water & nondissolved material; when some materials do not dissolve
Ex. Blood & components
DOUBLE ARROW MEANS…..
THE REACTION CAN OCCUR IN BOTH DIRECTIONS
ARROW MEANS “FORMS” OR “PRODUCES”
CHEMICAL EQUATION
H2O H+ + OH—
REACTANTS PRODUCTSBEFORE AFTER
Oven cleaner
Bleach
Ammonia solution
Soap
Sea water
Human bloodPure waterMilkNormalrainfall
Acid rainTomatojuice
Lemon juice
Stomach acid
NeutralIn
crea
sing
ly B
asic
Incr
easi
ngly
Aci
dic
Section 2-2
pH Scale
Go to Section:
1. What is pH used for?
To determine acids, bases and neutral substances
2. What does the pH value 7 mean?
There is an equal number of H+ ions and OH- ions. Example: pure water; neutral
3. Substances with a pH value above 7 are considered bases.
Under 7 are considered acids
4. What is the purpose for using a known base, a known acid, and distilled water?
The control part of the lab. To make sure the pH paper is working properly.
5. ACIDS, BASES AND pH
A water molecule can react to form ions.
H2O H+ + OH—
Water forms
hydrogen +hydroxideion ion
6. pH Scale= Potential or Power of Hydrogen
Indicates the concentration of H+ ions in a solution
Ranges from 0-14pH 7= H+ and OH- are
equal------pure water=7 NEUTRAL
7. Acidic-any compound that forms H+ ions in solution
pH below 7, more H+ ions than OH- ions
The lower the pH the greater the acidity
Ex: HCl-hydrochloric acidIn your stomach=______
8. Base-any compound that produces OH- ions in a solution
A.K.A= AlkalineLower concentrations of H+
ions than water, more OH- ions
pH value above 7Ex: oven cleaner=_______
E. BUFFERS
WEAK ACIDS OR BASESPREVENT SHARP CHANGES IN pH
Human body cells-pH6.5-7.5-homeostasis