Chp. 2- Water the solvent of life

Hydrogen Bond

a weak electrostatic attraction between one electronegative atom (such as oxygen or nitrogen) and a hydrogen atom covalently linked to a second electronegative atom

Bond dissociation energy

the energy required to break a bond

Hydrophilic

Nonpolar; describes molecules or groups that are insoluble in water

Amphipathic

containing both polar and nonpolar domains

Hydrophobic effect

 the aggregation of nonpolar molecules in aqueous solution, excluding water molecules; caused largely by an entropic effect related to the hydrogen-bonding structure of the surrounding water

Micelles

an aggregate of amphipathic molecules in water, with the nonpolar portions in the interior and the polar portions at the exterior surface, exposed to water

Van der Waals Interactions

aka london dispersion forces, Weak inter-molecular forces between molecules as a result of each inducing polarization in the other

Colligative properties

the properties of a solution that depend of the number of solute particles per unit volume; for example, freezing point depression

Osmosis

bulk flow of water through a semipermeable membrane into another aqueous compartment containing solute at a higher concentration

Equilibrium Constant, K_eq

 a constant, characteristic for each chemical reaction, that relates the specific concentrations of all reactants and products at equilibrium at a given temperature and pressure

Ion Product of Water

the product of the concentrations of H⁺ and OH^- in pure water, K_w= [H⁺][OH^-] = 1 x 10^-14 at 25°C

pH

the negative logarithm of the hydrogen ion concentration of an aqueous solution

Acidosis

A metabolic condition in which the capacity of the body to buffer H⁺ is diminished; usually accompanied by decreased blood pH

Alkalosis

a metabolic condition in which the capacity of the body to buffer OH^- is diminished; usually accompanied by an increase in blood pH

Conjugate acid-base pair

a proton donor and its corresponding deprotonated species; for example, acetic acid (donor) and acetate (acceptor)

Acid Dissociation Constants

the dissociation constant (K_a) of an acid, describing its dissociation into its conjugate base and a proton

pKa

analogous to pH, the negative logarithm of an equilibrium constant

Titration Curve

a plot of pH versus the equivalents of base added during titration of an acid

Buffers

a system capable of resisting changes in pH, consisting of a conjugate acid-base pair in which the ration of proton acceptor to proton donor is near unity

Optimum pH

the characteristic pH at which an enzyme has maximal catalytic activity