Acid - Base Reactions Strong Acids and Strong Bases

-Strong Acids (SA) dissociate to produce H+ ions
     -HCl, H2SO4, HClO4
-Strong Bases (SB) dissociate to produce OH- ions
     -NaOH, Ba(OH)2, LiOH
-When a SA and SB mix they form water and an ionic salt
-Total volume changes

pH and pOH

-pH is a measure of the hydrogen ions present in a solution

     pH = -log[H+]

-pOH is a measure of the hydroxide ions present in a solution 

     pOH = -log[OH-]

Example

-100mL of 0.250M HCl is added to 100mL of 0.250M LiOH

-Determine the mass of water produced.

 HCl + LiOH ----> HOH + LiCl

 0.250mol/L x .100L x 1/1 x 18g/1mol = 0.45g

-Determine the mass of the salt produced

 .45g x 1mol/18g x 1/1 x 42.4g/1mol =1.06g

Example

-100mL of .250M HCl is added to 200mL of .150M LiOH

-Determine the L.R.

 0.250mol/L x .100L = .0250mol

.150mol/L x .200L x 1/1 = .0300mol

L.R. HCl

-How much LiOH is left over when the reaction is complete?

0.206L x 0.150mol/L = .0300mol LiOH started with

0.0250mol x 1/1 = .0250mol LiOH used 

.0300mol - .0250mol = .0050mol LiOH left

-Determine [LiOH] after the reaction is complete

 0.0050mol x 1/.300L = 0.0167 M = [LiOH]

-Find the pOH of the final solution

 LiOH ----> Li+ + OH-

.0167M   .0167M  .0167M

pOH = -log[OH-]

pOH= -log[0.0167M]

       = 1.78

-T.H