Acids & Bases by W8Eo5Nf

VIEWS: 25 PAGES: 28

									Acids & Bases
             Naming Acids
• Binary acids
  – hydro (element) ic acid
• Ternary acids
  – replace the anion suffix -ate with -ic
  – replace the anion suffix -ite with -ous
            Name that Acid
•   HF
•   HBr
•   HNO3
•   HNO2
•   H2SO4
•   H2SO3
      Characteristics of Acids
      a.k.a. Arrhenius Acids
1. Acids are substances that ionize to
   form H+ in water.


                    H+ is the same as a proton, so
                  according to the Brønsted-Lowry
                   theory, Acids are proton donors
         Acid? Yes or No
•   H3PO4
                 An Acid must ionize
•   HF
              with H+ as the positive ion
•   KH
•   CH3COOH
•   CH3OH
•   KI
•   NaH
    H +   ions combine with water
• H+ ions do not exist by themselves in
  solution.
• H+ bonds with water to form hydronium ion




                               H3O+
2. Acids are electrolytes
  •   Ionize in water



The degree of ionization determines
if an acid is a weak or strong electrolyte
  Not many ions

                  LOTS of ions
         Strong or weak Acid?
• Acids listed in order of relative strength /
  ionization on Reference Table
   – HCl vs. H2CO3
   – Acetic acid vs. H3PO4
3. Acids react with active metals
 to produce H2 (g)
 active = (those listed above H2)

  Single Replacement Reaction
4. Acids change the colors of
   indicators
  –   blue litmus changes to red
5. pH < 7
6. Acids neutralized by bases and
   make a solution with pH = 7
7. Dilute acids taste sour
  –   citrus fruits (citric acid)
  –   vinegar (acetic acid)
       Characteristics of Bases
        a.k.a. Arrhenius Base
1. Defined as a substance that provides OH-
  ions to solution

Or according to the Bronsted-Lowry
 theory a base is a proton acceptor


         Ex: NH3 + HOH  NH4+ + OH-
            Naming Bases
• Name the cation (+)

• the names of   all bases end in hydroxide
• KOH
• Mg(OH)2
• NH4OH
2. Bases form electrolytic solutions
  – strong bases ionize completely
     • Group 1 hydroxides are strong bases


  – weak bases have low levels of
    ionization
     • all other bases are weak
              Base? Yes or No
•   NaOH
                     A base must ionize
•   CH3OH                  with the
•   C2H5OH              hydroxide ion
                   as the only negative ion
•   KOH
•   Mg(OH)2
•   NH4OH
3. Feel Slippery
      ex. soap
4. Taste bitter
      ex. soap
5. Change the colors of indicators
  –   Phenolphthalein
  –   Red litmus turns blue
6. pH > 7
7. Bases are neutralized by acids and make a
    solution with pH = 7
                        pH scale
• The pH scale is used to measure the [H+]
  and [OH-] in solution.


        [H+]
                                     [OH -]
0   1   2   3   4   5   6   7   8   9 10   11   12   13 14
Acids contain more H+
      than OH  -




      Bases contain more
             OH -

           than H +
         Water is Neutral
                                       -
  H2O + H2O           H3   O+   + OH
Water ionizes into equal concentrations of
hydronium ions (+) and hydroxide ions (-)

            [H+] = 1x10-7
           [OH -] = 1x10-7

           Neutral pH = 7
  [H +]      [OH -]     = 1  10       -14


• Because all acids and bases contain both of
  these ions you can determine the
  concentration of each.
                Simple pH
If [H+] = 10-4 then pH = 4

If [OH-] = 10-11 then [H+] = 10-3 and pH = 3


            pH and H are the same
             H and OH add to 14
          IGNORE THE NEGATIVE
            Each space on the pH scale is a
                    power of 10


        [H+]
                                      [OH-]
0   1   2    3   4   5   6   7   8   9 10   11   12   13 14
Compare pHs

 pH 7 and pH 8
 pH 3 and pH 5
pH 11 and pH 14
• You can calculate the (M)olar
  concentrations of H+ or OH- of
  any solution
             pH & indicators
                       Table M
• methyl orange            • litmus
  – red below 3.2            – red below 5.5
  – yellow above 4.4         – blue above 8.2
• bromthymol blue          • bromcresol green
  – yellow below 6.0         – yellow below 3.8
  – blue above 7.6
                             – blue above 5.4
• phenolphthalein
                           • thymol blue
  – colorless below 8.2
                             – yellow below 8.0
  – pink above 10
                             – blue above 9.6
Methyl orange

Bromthymol blue

phenolphthalein


litmus

Bromcresol green

Thymol blue


0   1    2    3   4   5   6   7   8   9 10   11   12   13 14
More acidic
greater [H+]
      &
 less basic
 less [OH-]



More basic
more [OH-]
     &
less acidic
 less [H+]
THE END

								
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