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Chapter 2 The molecular Basis of Life

STUDY
PLAY
every factor of 2 difference in [H+] = how many pH units?
.3
when diluting a stock solution the amount of stock solution you should use =
[what you want]/[what you need]*final volume
methods of finding pH
pH meter, pH paper, titrate solution
CO2 + H2O yields
H2CO3, weak acid
Keq =
[H+][A-]/[HA]
buffer
a solution of a weak acid and its conjugate base that resist changes in pH in both directions. buffer works best in the middle of its range where the amount of undissasociated acid is about equal to the amount of conjugate base.
ionization of water
very small: 10^-7 (pH=7)
water is the best solvent why?
-polarity, hydrogen bonding, small size, bent shape
why does surface tension occur?
meniscus forms with cohesion: water molecules at the surface hydrogen bond with those below them they create a net downward pull. adhesion:water molecules adhere to the glass and resist the downward pull.
why is water denser as a liquid than a solid?
ice- hydrogen bonds form a crystal structure with lots of spaces
how did life first begin, without a foundation?
-hot and molten earth, volcanoes released CO2, N2, and H2O vapor, H2O cools and forms oceans, reactions can occur in solution
theory of chemical evolution
simple chemical compounds in the ancient atmosphere and ocean combined to form more complex substances found in living cells using energy from heat + sunlight
1st law of thermodynamics
energy is conserved
exergonic
reactants loose potential energy
delta G =
delta H -T*delta S
energy started chemical evolution by the formation of
free radicals
free radicals are
highly reactive atoms with an unpaired electron broken off by photons
number of collisions depends on
temperature + concentration of reactants
the formation of H2CO (formaldehyde) +HCN was a critical step in chemical evolution because
energy from sunlight was converted to chemical energy (PE in chemical bonds)
functional groups
amino, carbonyl, carboxyl, hydroxyl, sulfyhydryl, phosphate