Acids and BasesLesson 1

Acid & Base Properties(Strong & Weak acids)

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.

The Arrhenius Theory of Acids and Bases

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

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

H+ is another way to show H3O+.

Hydronium ion

H3O+H+ + H2O ⇋

+

H+

H2O

Proton

Conjugate acids and bases

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.

Strong Acids

Weak Acids

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!

Balance these neutralization equations

H2SO4 + NaOH

HCl + Sn(OH)4

Homework:

Hebden: Pg 110 #1-2, Pg. 112 #3-4