Chapter 2: Water: The Medium of Life Flashcards
water and its ionization products, hydrogen ions and hydroxide ions, are __ __ of the __ and __ of many biomolecules
- critical determinants
- structure and functioning
represents an energized condition essential to biological mechanisms of energy transformation
difference in concentration of hydrogen ions on opposite sides of membrane
for a substance of this molecular weight that is neither metallic nor ionic, water has a substantially higher what?
- higher boiling point
- melting point
- heat of vaporization
- surface tension
__ __ of attraction between H2O molecules are high
intermolecular forces
Where is the maximum density of water found
liquid state
occur when two atoms in a molecule have substantially different electronegativity : one atom attracts electrons more than another, becoming more negative, while the other atom becomes more positive
permanent dipoles
__ __ in water is key to its properties
hydrogen bonding
the solvent properties of water are derived from its __ __
polar nature
H-bonding is __
cooperative
H2O molecule serving as an H-bond donor becomes a better H-bond __
acceptor
Properties of Water
- high dielectric constant
- forms H bonds with polar solutes
- hydrophobic interactions
- interaction with amphiphilic molecules
- ability of water to surround ions in dipole interactions and diminish their attraction for each other
- attractions between water molecules interacting with ions are much greater than tendency of oppositely charged ions to attract one another
high dielectric constant
examples of polar functional groups
- hydroxyl
- amines
- carbonyl
apparent affinity of nonpolar structures for one another
hydrophobic interactions
in actuality, the “attraction” between nonpolar solutes is an ____ process due to a net decrease in order
entropy-driven
compounds containing both strongly polar and strongly nonpolar groups
amphiphilic molecules
what disturbs the structure of liquid water, thereby changing its properties?
presence of dissolved substances
physical changes that result from adding solute to a solvent
Colligative properties
Colligative Properties of Water
- freezing point depression
- boiling point elevation
- vapor pressure lowering
- osmotic pressure effects
by imposing local order on water molecules, solutes make it more difficult for water to assume its __ __ (__) or escape into the atmosphere (__ or __)
- crystalline lattice (freeze)
- boil or vaporize
point at which the water is in a state of equilibrium, with the same number of water molecules transitioning from liquid to gas and from gas to liquid
vapor pressure
pressure necessary to push water back through the membrane at a rate exactly equaled by the water influx
osmotic pressure of the solution
when equilibrium is disturbed, the rates of the forward and reverse reactions change to relieve that stress and reestablish equilibrium
Le Chatelier’s principle
before equilibrium is reached, the concentrations of the reactants and products __
change
