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pH and Disassociation
H20 H+ + OH- Living organisms are composed mainly of
H2O. Some water molecules tend to separate into ions, forming solutions that are acidic or alkaline.
Therefore, in order to understand biochemical processes, we need to know a little about acids and bases
Ionization of Water
H2O H+ + OH-
Covalent dissociates
Bonding (splits)
Ionization of Water Same # of H+ as OH - = a neutral solution
Acids Acid = Have
more H+ ions in solution.
Examples
HCl H+ + Cl-
H2SO4 2 H++ SO4-
BASES Bases have more
OH- in solution
Examples:
NaOH Na+ + OH-
Al(OH)3 Al3+ + OH-
A pH scale (color coded)
What do the pH #’s mean?
pH = a measure of H+ concentrations
HUMAN pH Our bodies have a pH
of 7.4 Stomach pH =1 to 2 Acceptable range is
6.5- 7.5, otherwise its lethal (coma or death)
HOMEOSTASIS A mechanism to maintain body’s
stabilization, Human pH range is between 6.5 -7.5 One way to keep the body stable is through
pH and buffers.
H+ + HCO32- H2CO3 H2O + CO2
carbonic
acid
BUFFER Buffers are weak acids & bases that rxt with strong acid & bases in the body to maintain homeostasis.
A buffer is a substance which accepts H+ ions or gives off H+ in order to maintain the pH of a system
New Stuff =Water Polarity
Polarity H2O is a polar molecule
because of the unequal distribution of e- between hydrogen and oxygen.
Neg. pole near oxygen atom & positive pole is between the hydrogens
Cohesion The attraction
between molecules of the same substance Explains why H2O
beads up Explains why some
insects & spiders can walk on water
Adhesion Attraction between
molecules of different substances
Capillary Action Due to adhesion
between H2O & glass, the water can rise in a narrow tube against the force of gravity.