Basic Chemistry
Chapter 2 – Part 3
Organic vs. Inorganic
Compounds
 Organic Compounds – Carbon-containing compounds.
 Include: Carbohydrates, lipids, proteins, and nucleic acids.
 All are fairly or very large covalently bonded molecules.
 Inorganic Compounds – Do not contain carbon.
 Tend to be simpler, smaller molecules.
 Include: Water, salts, and many (but not all) acids and
bases.
 Exception: Carbon dioxide (contains carbon but is
classified as inorganic)
Water
 Most abundant inorganic compound in the body
(accounts for 2/3 of body weight).
 There are four properties of water that make water so
vital:
1. High Heat Capacity
2. Polarity/Solvent Properties
3. Chemical Reactivity
4. Cushioning
High Heat Capacity
 It absorbs and releases large amounts of heat before
its temperature changes appreciably.
 Prevents sudden changes in body temperature.
The hydrogen
bond is what
gives water its
heat capacity.
Polarity/Solvent Properties
-
 Because of its polarity, water is an excellent solvent.
 Molecules cannot react chemically unless they are in
solution, so virtually all chemical reactions in the body
depend upon water’s solvent properties.
 Because nutrients, respiratory gases, and wastes can
dissolve in water, water can act as a transport and
exchange medium in
the body.
+
Polarity/Solvent Properties (continued)
 Specialized molecules that lubricate
the body also use water as their solvent.
 Examples:
 Mucous that eases feces along the large
intestines
 Saliva which moistens food and
prepares it for digestion
 Serous fluids which reduce friction
between internal organs
 Synovial fluids which “oil” the ends
of bones as they move within joint
cavities.
Chemical Reactivity
 Water is an important reactant in some
types of chemical reactions.
 Example: To digest foods, water molecules are added to
the bonds of the larger molecules.
 Such reactions are called hydrolysis reactions.
 Condensation reactions occur in
the synthesis of biological molecules,
including proteins, carbohydrates,
fats, and nucleic acids.
 These reactions join smaller
molecules into larger molecules.
Cushioning
 Water also serves a protective
function.
 Examples:
 Cerebrospinal fluid forms a
cushion around the brain that
helps to protect it from physical
trauma.
 Amniotic fluid protects a
developing fetus in the mother’s
womb.
Salts
 The salts of many metal
compounds are commonly
found in the body.
 Most plentiful salts are calcium
and phosphorus (found mainly
in the teeth and bones).
 When dissolved in body fluids,
salts easily separate into their
ions
 Called dissociation and occurs
rather easily by the polar water
molecules
Salts
 Salts, both in their ionic forms and in combination with
other elements, are vital to body functioning.
 Examples:
 Sodium and potassium ions are essential for nerve impulse.
 Iron forms part of the hemoglobin molecule that transports
oxygen within red blood cells.
Salts and Electrolytes
 Because ions are charged particles, all salts are
electrolytes – substances that conduct an electrical
current in solution.
 When ionic or electrolyte imbalance is severely disturbed,
virtually nothing in the body works.
Acids and Bases
 Like salts, acids and bases are electrolytes.
 They ionize and then dissociate in water and can then
conduct an electrical current.
Characteristics of Acids
 Sour taste
 Can dissolve many metals or “burn” a hole in your rug.
 Substance that can release hydrogen ions (H+) in
detectable amounts.
 When acids are dissolved in water, they release hydrogen
ions and some ions.
 Also defined as a proton donor.
Strong Acids
 Strong Acids – Acids that ionize completely and liberate
all of their protons.
 Examples include: Hydrochloric acid produced by
stomach cells that aid in digestion.
HCl → H+ + Cl(Hydrochloric
Acid)
(proton)
(anion)
Weak Acids
 Weak Acids – Acids that ionize incompletely.
 Examples: Carbonic acid and acetic acid
H2CO3 → H+ + HCO3- + H2CO3
(Carbonic Acid)
(proton)
(anion)
(Carbonic Acid)
Characteristics of Bases
 Bitter Taste
 Feel Slippery
 Proton Acceptors
 Releases the hydroxyl ion (OH-) and some cations.
NaOH → Na+ + OH(Sodium Hydroxide)
(cation)
(hydroxyl ion)
Strong vs. Weak Bases

Strong Base – Any base containing OH NaOH is a strong base because it’s an avid proton (H+)
seeker.
 Weak Base – A base that does not contain OH Bicarbonate ion (HCO3-) is an important base in the
blood and is a fairly weak base.
Neutralization Reactions
 When acids and bases are mixed, they react with
each other (in an exchange reaction) to form water
and a salt.
 Called a Neutralization Reaction.
HCl + NaOH → H2O + NaCl
(acid)
(base)
(water) (salt)
pH: Acid Base
Concentrations
 The relative concentration
of hydrogen and hydroxyl
ions in various body fluids
is measured in
concentration units called
pH units.
 pH scale: 1-14
10
11
12
13
14
More Acidic H+
1
2
3
4
5
6
7
8
9
Neutral
More Basic OH-
0
• Litmus paper is used as an indicator
for acids and bases.
Acidic turns blue litmus  to red
Basic turns red litmus  to blue
If there are more H+ than OH-, then the chemical is an acid.
H+
H
O OHIf there are Less H+ than OH-, then the chemical is a base.
H+
H
O OHIf there are equal amounts of H+ and OH-, then the chemical is
neutral.
+
H
H
O OH-
.
Buffers
 Living cells are extraordinary sensitive to even slight
changes in pH.
 Acid-base balance is carefully regulated by the kidneys,
lungs, and a number of chemicals called buffers, which
are present in body fluids.
 Weak acids and weak bases are important components of the
body’s buffer systems.
Blood pH
 Because blood comes into close contact with nearly
every body cell, regulation of blood pH is especially
critical.
 Blood pH has a narrow range of 7.35 - 7.45.
 When blood pH changes more than a few tenths of a pH
unit from these limits, death is possible.
 Example: When blood pH dips into the acid range, the amount
of life-sustaining oxygen that the hemoglobin in blood can
carry to body cells begins to decline rapidly to dangerously
low levels.