Transcript Solutions and solventx

Solutions and solvent
Solutions & Suspensions
• Water is usually part of a
mixture.
• There are two types of mixtures:
–Solutions
–Suspensions
Solution
• Ionic compounds disperse as ions in
water
• Evenly distributed
• SOLUTE
– Substance that is being dissolved
• SOLVENT
– Substance into which the solute
dissolves
Solution
Suspensions
• Substances that
don’t dissolve but
separate into tiny
pieces.
• Water keeps the
pieces suspended
so they don’t
settle out.
The pH Scale
concentration of H+ ions
• Indicates the
0 – 14
• Ranges from
• pH of
(equal
7 is neutral
amounts H+ and OH-)
• pH 0 up to 7 is acid … H+
• pH above 7 – 14 is basic… OH• Each pH unit represents a factor of 10X
change in concentration
• pH 3 is 10 x 10 x 10 (1000) stronger than a
pH of 6
ACIDS
• Compound that releases Hydrogen ions (H+)
Acids
• Strong
Acids
have a pH
of 1-3
• Produce
lots of
H+ ions
Examples of Common Acids
•
•
•
Hydrochloric acid – HCl
Hydrosulfuric acid – H2SO4
Nitric acid – H2NO3
What do these formulas have in common?
Acetic Acid - Vinegar
HC2H3O2
Salicylic Acid
Natural Source – Willow bark
Used in
Lactic Acid
•Found in yogurt, cottage cheese and
sourdough bread
•Causes muscle “burn” when it builds
up inside cells
Citric Acid
•Found in citrus fruits
(lemons, oranges, grapefruit)
•Flavoring in soft drinks
Formic Acid
• Produces the burning sensation in
the venom of ants and bees
HCO2H
Amino Acids
• “Building blocks” of protein molecules
Nucleic Acids
• Deoxyribonucleic Acid
DNA
• Ribonucleic Acid
RNA
Bases
•Bases are compounds that release
Hydroxide ions (OH -) in water.
• Also called alkalines.
Bases
• Strong
Bases have
a pH of 11
to 14
• Contain
lots of OHions and
fewer H+
ions
Examples of Common Bases
Sodium hydroxide – NaOH
Calcium hydroxide – CaOH
Magnesium hydroxide – Mg(OH)2
Most soaps and detergents are basic
All compounds are either
Acids, Bases, or Neither
Chemical Formula
HF
H2SO4
CaOH
Mg(OH)2
C6H12O6
HCl
NaCl
Al(OH)2
Acid
Base
Neither
All compounds are either
Acids, Bases, or Neither
Chemical Formula
HF
H2SO4
CaOH
Mg(OH)2
C6H12O6
HCl
NaCl
Al(OH)2
Acid
Base
Neither
XX
XX
XX
XX
XX
XX
XX
XX
acid rain (NOx, SOx)
pH of 4.2 - 4.4 in
Washington DC area
pH
0-14 scale for the chemists
2
3
4
5
acidic
(H+) > (OH-)
normal rain (CO2)
pH = 5.3 – 5.7
6
7
8
neutral @ 25oC
(H+) = (OH-)
distilled water
fish populations
drop off pH < 6
and to zero pH < 5
9
10
11
basic or alkaline
(H+) < (OH-)
natural
waters pH =
6.5 - 8.5
12
pH
The biological view in the human body
acidic
1
2
3
4
5
6
basic/alkaline
7
8
9
10
Tortora & Grabowski, Prin. of Anatomy & Physiology, 10th ed., Wiley (2003)
11
Determining a compound’s identity from its pH value
pH
1.3
11.47
7.001
0.1
6.999
3.89
13.0
0.0
Acid
Base
Neutral
Determining a compound’s identity from its pH value
pH
1.3
Acid
Base
XX
11.47
XX
7.001
XX
0.1
XX
6.999
XX
3.89
XX
XX
13.0
0.0
7.0
Neutral
XX
XX
Most living things must live in an environment of
pH 6.5 – 7.5
HOWEVER, there are some exceptions:
•Acidophiles “acid-loving” - archaebacteria that live
in highly acidic environments. They have evolved
homeostatic mechanisms to maintain their internal
pH at a constant level (usually 7.2).
Example: Lactos acidophilus live in the human
stomach fluid which is pH 2
• Specialized cells in stomach lining make HCl
“stomach acid” of pH 1
Parietal Cells
•
Azalea plants need acidic soil of pH 4.5 to bloom
Soil pH
• Alkaline soil makes hydrangeas pink
• Acidic soil makes hydrangeas blue
Acids and Bases
• The H+ ions formed in acids (and
the OH- ions formed by bases)
can cause certain chemical
reactions that may interfere with
a cell’s normal functioning (can
lead to cell death)
• Our stomachs contain hydrochloric
acid (pH of 1-2) that causes
chemical reactions with bacteria in
food to kill them
• (our stomach is protected by a
layer of mucus)
Buffers
• Weak acids or bases that react with
strong acids or bases to prevent sharp,
sudden changes in pH
• Produced naturally by the body to
maintain homeostasis
Weak Acid
Weak Base
Blood pH and Buffers
• Normal pH of blood between 7.35 - 7.45
• Less than 6.8 or greater than 7.8 is deadly
• Natural Buffers in your body help prevent any
large change in blood pH; keeps you healthy homeostasis