16.1b: Acid strength and equilibrium position

Strong acids ionize completely, strong electrolyte reacts completely with water to form H3O+

assume the [H3O+] is equal to the initial acid conc.

shown as >99% over the yield/equilibrium arrow

Strong Acids to know HCl, HBr, HI, HClO4, H2SO4, HNO3

>99%

Weak Acids compounds with acidic properties that

ionizes partially in solution weak electrolytes can assume any acid not on the SA list is

weak Ex. acetic acid, lactic acid, citric acid

reacts partially with water to form relatively few H3O+

must calculate [H3O+] since small amount of initial acid ionizes

shown as <50% over the yield/equilibrium arrow

<50%

acidic: weak

bonds polar

bonds

non-acidic strong bonds nonpolar

bonds

most make OH- ions strong bases dissociate into OH- ions and

metal ion Ca(OH)2 Ca2+ + 2OH-

LiOH Li+ + OH-

weak bases take a H+ from water and make OH-

NH3 + H2O NH4+ + OH-

C6H5NH2 + H2O C6H5NH3+ + OH-

Weak Basesdo not contain OH-

accepts H+ from H2O to make OH-

also called %rxtn. with water in acid-base sol’n theory, reaction with water

means the same as ionization in water the higher the conc. of the weak acid

sol’n the lower its % ionization if we know the pH or initial acid conc. of a

weak acid solution we can calculate the % ionization

formula

p = % ionization[HA] = initial conc. of weak acid

3[ ]100%

[ ]

H Op

HA

Orange juice has a citric acid concentration of 0.23M and at equilibrium 3.1% has reacted to form H3O+ . Calculate the [H3O+ ]

Solution use formula to solve

3[ ]100%

[ ]

H Op

HA

3[ ]3.1%

0.23

H O

M

33.1

[ ] 0.23100

H O M

Plug in and solve for [H3O+ ].

3[ ] 0.00713H O M or3

3[ ] 7.13 10H O M

Textbook p721 #2-7, 9, 11, 13, 14