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Taste bitter (baking soda)
Change litmus paper blue
Feel slippery
Are electrolytes that conduct electricity
Neutralize acids
Properties of Bases
Ex: NaOH, Ca(OH)2, KOH, Zn(OH)2 -- notice they all contain OH.
Taste sour (vinegar, lemon juice)
Change litmus paper red
React with metals such as Mg and Zn to make H2
Mg(s)+ 2 HCl (aq) MgCl2 (aq) + H2(g).
Are electrolytes that conduct electricity
Neutralize bases
Properties of Acids
Ex: HCl, HNO3, H2SO4 –notice they all contain H.
Salts
A salt is the neutralization product when an acid and a base react to produce water.
HCl + NaOH NaCl + H2O
Notice, a salt does not contain H, or OH.
Arrhenius acid
HCl
Arrhenius base
NaOH Na+ + OH-
H+ + Cl-
produces H+ in solution
produces OH- in solution
H+ is called a proton
Bronsted-Lowry Theory of Acids and Bases
-more general theory-to accommodate reactions at equilibrium.-acids as proton donors-bases as proton acceptors
H+
Bronsted Acid
H+
HCl + H2O
Bronsted Base
NH3 + H2O ⇄
A proton donor
A proton acceptor
Chemistry 12
Chemistry 12
H3O+ + Cl-
NH4+ + OH-
weak
strong
H+H+
Write a Bronsted reaction for the base HCO3-
base acid acid base
HCO3- ⇄ H2CO3 + OH- + H2O
weak
These are called “Conjugate acid-base pairs”They differ by one proton H+
HCO3- and H2CO3 H2O and OH-
5. H+ is the same as H3O+
4. Bronsted acids donate a proton to water to form H3O+
3. Arrhenius acids dissociate in water to form H+
2. Bronsted bases accept a proton from water to produce OH-
1. Arrhenius bases dissociate in water to produce OH-
In Summary
Conjugates A conjugate acid-base pair (conjugate pair) is a pair of chemical species which differ by only one proton (H+)
NH4+, NH3
A conjugate acid is the member of conjugate pair that HAS the extra proton.
NH4+
A conjugate base is the member of the conjugate pair that LACKS the extra proton.
NH3
NH4+ NH3
Fe(H2O)63+
OH-
HCO3-
HPO42-
PO43- HPO4
2-
H2PO4-
H2CO3
H2O
One more H+ 1 less H+
Conjugate BaseConjugate Acid
C6H5COOH C6H5COO-
C6H5OH C6H5O-
Fe(H2O)5(OH)2+
H+ gives a +1
Charge.
Acids and Bases Chart p334
Relative Strengths of Bronsted-Lowry Acids and Bases
Aqueous solutions at room temperature.
HCl + H2O H3O+ + Cl-
Use a “” and not “⇄” because it is not an equilibrium situation.
Have very large Ka’s, that is why you do not find them on the chart.
Produce large amounts of H3O+.
Are good conductors.
Completely ionize in water
Left side of Acid Chart -top six- Strong Acids
Weak Acids Left side of the Acid Chart below the top six. Do not completely ionize in water.Are poor conductors.Produce small amounts of H3O
+.
Have small Ka’s, you will find Ka values on the chart.Use a “⇄” and not “” It means they are Equilibrium situations!
HF + H2O ⇄ H3O+ + F-
Ka = [H3O
+][F-] = 3.5 x 10-4 from page 334
[HF] Water is not included because it is a pure liquid! Its concentration is constant!
You can also write:
HF + H2O ⇄ H3O+ + F-
HF + H2O ⇌ H+ + F-
[H+][F-]
Ka = = 3.5 x 10-4
[HF]
We use H+ and H3O+ interchangeably. They mean
the same thing!