Ch. 3 - pH

 Rate is low  # of hydronium ions = # of hydroxide ions Dissociation of water

 Substance that increases (H+) = acid  Ex) HCl  H + +Cl-  Substance that reduces (H + ) = base  Ex) NH3 + H +  NH4 or NaOH  Na + + OH -   Acids and Bases

 (H + )(OH - ) =  pH = -log(H+)  If (H + ) is then the –log10 -7 = -(-7) = 7  ***pH declines as (H + ) increases  Ex) A solution with a pH of 10  (H+) = and (OH) =  ****each pH unit represents a tenfold difference in H+ and OH- concentration  Ex) Sol’n A (pH 3) vs Sol’n B( pH 6)  Solution A is 1000 times mores acidic than Solution B pH scale

 1. Which is more acidic? (H+) of 1.0 x or 1.0 x  2. Which is more basic? (H+) of 1.0 x or 1.0 x  3. What is the H+ concentration of stomach acid? Practice

(H3O+) or (H+)Scientific notationpH More practice

 As (H+) gets smaller, scientific notation exponents get bigger, and pH goes up.  As (H+) gets larger, scientific notation exponents get smaller, and pH goes down. Summary