chem ch 17

Properties of acids

sour taste, can dissolve many metals, can neutralize bases, change blue litmus paper to red

Binary acid

acidic hydrogen is attached to a nonmetal atom

Oxyacid

acidic hydrogen is attached to an oxygen atom

Carboxylic acid

has a COOH group (HC2H3O2, H3C6H5O7; only first H in formula is acidic)

Properties of bases

bitter taste, feel slippery, can neutralize acids, change red litmus paper to blue

Arrhenius definition of acid

produces H+ in solution(H+ ions always associate with water to form H3O+)

Arrhenius definition of base

produces OH- in solution

Bronsted-Lowry definition of acid

H+ donor

Bronsted-Lowry definition of base

H+ acceptor

Arrhenius acid-base rxns

H+ from acid combines with OH- from base to form H2O, cation from base combines with anion from acid to form a salt

Bronsted-Lowry definition of acid-base rxns

Any rxn involving H+ transfer from one molecule to another is an acid-base rxn

Amphoteric substances

can act as either acid or base, have both a transferable H+ and an atom with lone-pair electrons

Conjugate acid-base pairs

in a B-L acid-base rxn, og base becomes acid in rev rxn, og acid becomes base in rev rxn; each reactant and product it becomes is a conjugate pair

Strong acid

strong electrolyte, practically all molecules ionize

Strong base

strong electrolyte, practically all molecules form OH- ions

Weak acid

weak electrolyte, only small percentage of molecules ionize

Weak base

weak electrolyte, only small percentage of molecules form OH- ions

Acid strength is measured by

size of equilibrium constant when acid reacts with H2O, eq constant for this rxn is called the acid ionization constant(Ka), larger Ka=stronger acid

Autoionization

water is amphoteric, and can act with itself as both an acid and base to form ions; all aqueous solutions contain both H3O+ and OH- in equal []s

Ion product of water(Kw)

=[H3O+]x[OH-]=1.00x10^-14 at 25 C, [H3O+] and [OH-] are inversely proportional

1 pH unit corresponds to

a factor of 10 difference in acidity

Can express strength of acid/base through pKa/b

stronger acid/base, smaller pKa/b

Finding pH of a strong acid

[H3O+]=[HA] (concentration of acid=concentration of H3O+)

Finding pH of a weak acid

write equation for acid and prepare ICE table; set up Ka equation and solve for x; find [H+] or [H3O+] and then pH

% ionization

=[ionized acid]/[initial acid]*100

Cation of strong base and anion of strong acid

do not ionize water, do not affect pH

Cation of weak base and anion of weak acid

do ionize water, do affect pH

The stronger the acid

the weaker the conjugate base

Ka*Kb=

Kw

The stronger the base;the weaker the conjugate acid

Polyprotic acid-acid that can donate more than one proton per molecule to a sol’n

Lewis acid-base theory

focuses on transferring an electron pair

Lewis acid

lone e- pair acceptor

Lewis base

lone e- pair donor