2.1 Acids and Bases: Chemical Properties

acid

proton donor

base

proton acceptor

strong acid

acid that completely dissociates to yeild h+ in water

weak acid

acid that partially disociates in water

strong base

base that completely ionizes oh in water

weak base

base that partially ionizes in water

Ka charaterizes the

acid dissociation constant

HCL is a

strong acid

K_a =

[product}/[reactant]

strong acids have a ka

above 1

weake acids have a ka

below 1

many biological molecules are

weak acids

the state of weak acids depends on

pH

buffers

maintain pH of solutions

switterion

containing both positive and negative charge with a net charge of 0

isoelectric point

the ph in which the average charge sums to 0

pI =

pKa1 + pKa2/ 2

proteins contain many

titratable groups

solubility in water depends

partly on surface charges

pH of proteins affect

solubility

when pH is greater than Pi

solubile

pH = pI

promotes aggregation and protein is less soluble

pH is less than Pi

positive charges repel making it more soluble

salts increase

solubility of proteins