Acids and Bases. General properties

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Slide 1

Acids and Bases

PGCC CHM 101 Sinex

Slide 2

General properties

ACIDS

Taste sour

Turn litmus

React with active metals – Fe, Zn

React with bases

BASES

Taste bitter

Turn litmus

Feel soapy or slippery (react with fats to make soap)

React with acids

blue to red

red to blue

Slide 3

Definitions

Acids – produce H+

Bases - produce OH-

Acids – donate H+

Bases – accept H+

Acids – accept e- pair

Bases – donate e- pair

Arrehenius

Bronsted-Lowry

Lewis

only in water

any solvent

used in organic chemistry,

wider range of substances

Slide 4

Examples

Arrhenius

Bronsted-Lowry

Lewis

HCl

NaOH

HCl

NH3

:NH3

BF3

HCN

The hydrogen ion in aqueous solution

H+ + H2O  H3O+ (hydronium ion)

Slide 5

The Bronsted-Lowry Concept

Conjugate pairs

HCl Cl-

CH3COOH CH3COO-

NH4+ NH3

HNO3 NO3-

How does a conjugate pair differ?

H+ transfer

Slide 6

Neutralization

In general: Acid + Base  Salt + Water

All neutralization reactions are double displacement reactions.

HCl + NaOH  NaCl + HOH

HCl + Mg(OH)2 

H2SO4 + NaHCO3 

Slide 7

H2O  H+ + OH-

Does pure water conduct electrical current?

(H+)(OH-) = 10-14

For pure water: (H+) = (OH-) = 10-7M

This is neutrality and at 25oC is a pH = 7.

Water is a very, very, very weak electrolyte.

How are (H+) and (OH-) related?

water

Slide 8

HA

Let’s examine the behavior of an acid, HA, in aqueous solution.

What happens to the HA molecules in solution?

Slide 9

HA

H+

A-

Strong Acid

100% dissociation of HA

Would the solution be conductive?

Slide 10

HA

H+

A-

Weak Acid

Partial dissociation of HA

Would the solution be conductive?

Slide 11

HA

H+

A-

Weak Acid