Acids and Bases: an Introduction

Sour Taste Electrolytes Identified by the presence of H+

ions (Arrhenius). Proton (H+) donor (Bronsted-

Lowry). Common Acids: vinegar, citric

acid, sulfuric acid, hydrochloric acid.

Acids

An acid H+ in waterAn acid H+ in water

ACIDS

HNO3, nitric acidHNO3

HNO3 H+ + NO3-

Strong acids are strong electrolytes and completely dissociate in water.

An acid H+ in waterAn acid H+ in water

ACIDS

HCl hydrochloricHBr hydrobromicHI hydroiodicHNO3 nitric

H2SO4 sulfuric

HNO3

The following are examples of strong acids.

The Hydronium Ion

HCl

H2O H3O+

Cl-

hydronium ion

Free H+ is highly reactive and does not actually exist in nature. It reacts with water to form the hydronium ion, H3O+.

HCl (aq) H3O+ (aq) + Cl-

(aq)

Weak Acids

WEAK ACIDS are weak electrolytes and do not completely dissociate in water.

CH3CO2H acetic acid

H2CO3 carbonic acid

H3PO4 phosphoric acid

Dissociation of a Weak Electrolyte

Bitter taste Slippery Like acids, they are electrolytes Identified by the presence of OH-

ions (Arrhenius). Proton (H+) acceptor (Bronsted-

Lowry).

Bases

Base OH- in water Base OH- in water

BASES

NaOH(aq) Na+(aq) + OH-

(aq)

NaOH is a strong base

Strong bases are strong electrolytes and soluble in waterStrong bases are strong electrolytes and soluble in water

04m08an104m08an1

Based on the concentration of H+

or OH- ions in a solution. Strong Acids/Bases: completely

dissociate into ions in a solution. Weak Acids/Bases: do NOT

completely dissociate into ions in a solution.

Strength of Acids and Bases

Conjugate Acids/Bases

Acids and bases are related to each other through the addition/loss of hydrogen ions Conjugate acid-base pairs

Acids produce conjugate bases Bases produce conjugate acids

Conjugate Examples

HA + H2O H3O+ + A-

HNO3 + NH3 NH4+ + NO3

-

Conjugate Acid/Base Strength

Stronger the acid, the weaker the conjugate base

Stronger the base, the weaker the conjugate acid

Weak acids/bases have strong conjugate bases/acids

Strong Acid Example: HCl

Weak Acid Example: CH3CO2H

“BIG 6”---Strong Acids

(Know them!!) HClO4

HI HCl HNO3

HBr H2SO4

Strong Bases (Know them!!)

Group I metal hydroxides (NaOH, KOH, etc.)

Soluble/Slightly soluble Group II metal hydroxides ( Ca(OH)2, Sr(OH)2, Ba(OH)2 )

Binary acids– containing only 2 elements (one is

hydrogen) 1) Prefix “hydro—” with binary acid 2) root name for second element 3) End the name with “IC acid”

Oxyacids– acids containing hydrogen, oxygen, and a nonmetal 1) use the given polyatomic ion name from anion 2) add “IC acid”

Acid Nomenclature

Write name

Example 1: HBr

Write name.

Now you try, HCl

Write chemical formula

Example 2: Hydrofluoric acid

Now you try, hydriodic acid.

Write the name.

Example 3: H2SO4

Write the name.

Example 4: HClO2

HClO3

HClO HClO4

Try:

Name of cation, name of

anion/hydroxide

Ex. NaOH

Base Nomenclature

Briefly brainstorm how we

measure the amount of hydrogen ions in a solution? How can we quickly measure the acidity or basicity of a solution?

Brainstorm…