Introduction to
Acids, Bases
Arrhenius Definition of
Acids and Bases
 Acids dissociate to produce
H+ ions in aqueous (water)
solutions
HCl
H+ (aq) + Cl- (aq)
 Bases dissociate to produce
OH- ions in aqueous (water)
solutions
NaOH
Na+ (aq) + OH-(aq)
Dissociation

Dissociation: when a compound splits
apart into ions in solution.
How might these dissociate?
H2SO4
DO NOW:
KOH
Packet page 3, #7
Practice Writing
Dissociation Equations
Note:
 Acids and Bases are only reactive if their
ions are dissociated (when aqueous)

HCl (l) = hydrogen chloride
 HCl (aq) = hydrochloric acid

Getting to Know Some Acids
Some Common Acids
See Table K
HCl
hydrochloric acid
HNO3
nitric acid
H3PO4
phosphoric acid
H2SO4
sulfuric acid
HC2H3O2 acetic acid
6
The Hydronium Ion (H30+)

Acids produce the H+ ion


This is just a “bare proton”
and is very reactive.
It immediately forms a
coordinate covalent bond
with nearby water
molecules to form (H30+).
Do Now:
Draw the formation of the
Hydronium Ion
Organic Acids
Contain carbon
 Only one of the hydrogens is “acidic” and
dissociates in solution


Ex:
Acetic Acid
 HC2H3O2
or
CH3COOH
Naming Acids (Honors)

Binary Acids

(Contain 2 elements only)

Ex:
HCl, HBr, H2S, HF
Hydro
__________ ic Acid
Naming Acids (Honors)

Ternary Acids
(Contain hydrogen and a polyatomic ion)
 Do NOT start with “Hydro”


Look at name of polyatomic ion

If it ends in “ate” the acid ends in “ic”

If it ends in “ite” the acid ends in “ous”
Name These Acids (Honors)
 HBr
 HClO
 HNO3
 HBrO
 H3PO4
 HClO4
 HNO2
 H2S
 H2C2O4
 HIO3
Name These Acids (Honors)
HBr = hydrobromic acid
HClO = hypochlorous acid
HNO3 = nitric acid
HBrO = hypobromous acid
H3PO4 = phosphoric acid
HClO4 = perchloric acid
HNO2 = nitrous acid
H2S = hydrosulfuric acid
H2C2O4 = oxalic acid
HIO3 = iodic acid
Getting to Know Some Bases
Naming Bases

All Arrhenius bases contain the hydroxide ion

Name ends in “hydroxide”


Ex: LiOH = lithium hydroxide
Note:

There are “Non” Arrhenius Bases, more on them
later
Some Common Bases
See Table L
NaOH
sodium hydroxide
KOH
potassium hydroxide
Ba(OH)2
barium hydroxide
Mg(OH)2
magnesium hydroxide
Al(OH)3
aluminum hydroxide
15
Important Note

There are no “organic bases” (containing
carbon).
C2H5OH for example is not a base.
It is an alcohol.
The OH on this molecule does not
dissociate to form OH- (hydroxide ion)
Salts

“Salts” are ionic compounds that are not
acids or bases.
Metal cation (+) & nonmetal anion (-)
 Ex: NaCl, MgSO4, Li2S

Learning Check
Acid, Base
or Salt
Name
CaCl2
______
_______________
KOH
______
_______________
Ba(OH)2 ______
_______________
HBr
______
_______________
H2SO4
______
________________
18
Answers
Acid,Base
or Salt
Name
CaCl2
salt
calcium chloride
KOH
base
potassium hydroxide
Ba(OH)2
base
barium hydroxide
HCl
acid
hydrochloric acid
H2SO4
acid
sulfuric acid
Electrolytes

Acids & Bases & Salts are electrolytes
Produce free ions when dissolved
 Solutions will conduct.
 More concentrated = more conductive.

Do Now:
Practice Ditto
on Identifying
Electrolytes
http://www.kentchemistry.com/links/A
cidsBases/Electrolytes.htm
Taste & Feel

Acids: taste sour and give a burning
sensation if touched

Bases: taste bitter and feel slippery if
touched
DO NOT attempt to
determine an acid or
base by taste or touch
ever in the lab!
Let’s Review

Which substance, when dissolved in
water, forms a solution that conducts an
electric current?
(1) C2H5OH
(3) C12H22O11
(2) C6H12O6
(4) CH3COOH
A solid substance was tested in the
laboratory. The test results are listed below.
• dissolves in water
• is an electrolyte
• melts at a high temperature
Based on these results, the solid substance
could be
(1) Cu
(3) C
(2) CuBr2
(4) C6H12O6
The compound HNO3 can be described as an
(1) Arrhenius acid and an electrolyte
(2) Arrhenius acid and a nonelectrolyte
(3) Arrhenius base and an electrolyte
(4) Arrhenius base and a nonelectrolyte

Based on Reference Table F, which of
these salts is the best electrolyte?
A. sodium nitrate
B. magnesium carbonate
C. silver chloride
D. barium sulfate

A substance that conducts an electrical
current when dissolved in water is called
(1) a catalyst
(2) a non-electrolyte
(3) a metalloid
(4) an electrolyte

Which compound is an Arrhenius acid?
(1) CaO
(2) K2O
(3) HCl
(4) NH3

When one compound dissolves in water,
the only positive ion produced in the
solution is H3O+(aq). This compound is
classified as
(1) a salt
(2) a hydrocarbon
(3) an Arrhenius acid
(4) an Arrhenius base

Which substance is an Arrhenius acid?
(1) Ba(OH)2
(2) H3PO4
(3) CH3COOCH3
(4) NaCl

Which compound releases hydroxide ions
in an aqueous solution?
(1) CH3COOH
(2) HCl
(3) CH3OH
(4) KOH

An Arrhenius base yields which ion as the
only negative ion in an aqueous solution?
(1) hydride ion
(2) hydronium ion
(3) hydrogen ion
(4) hydroxide ion

The compound NaOH(s) dissolves in water
to yield
(1) hydroxide ions as the only negative ions
(2) hydroxide ions as the only positive ions
(3) hydronium ions as the only negative ions
(4) hydronium ions as the only positive ions
How are HNO3(aq) and CH3COOH(aq) similar?
(1) They are Arrhenius acids and they turn blue
litmus red.
(2) They are Arrhenius acids and they turn red litmus
blue.
(3) They are Arrhenius bases and they turn blue
litmus red.
(4) They are Arrhenius bases and they turn red
litmus blue.
Acids “Corrode” Certain Metals

See Reference Table J


Metals above Hydrogen on the table will react
with acids to form a salt and H2 gas
Single Replacement Reaction
2Zn(s) + 2HCl(aq)
ZnCl2(aq) + H2(g)
Will an acid react with these metals?

If so complete and balance the single
replacement reaction.
Mg + HNO3
Cu + HCl
Ca + H2SO4
Answers
Mg + 2HNO3
Cu + HCl
Ca + H2SO4
Mg(NO3)2 + H2
No reaction Cu in below
hydrogen on Table J
Ca(SO4) + H2
 Bases
DO NOT corrode metals
DO NOW:
Packet page 2 and 3, # 4, #5



Interactive:
Acid, Bases and Metals BBC (good for Indicators)
http://www.bbc.co.uk/schools/ks3bitesize/science/chemical_material
_behaviour/acids_bases_metals/activity.shtml
pH Scale

Used to help determine how acidic or basic
something is.

pH = 7 Neutral

pH < 7 Acidic

pH > 7 Basic
Acids & Bases Neutralize Each
Other

H+ ion and OH- ions will join together to form
neutral water.

Reaction is slightly exothermic (See Table I)
H+ (aq) + OH- (aq) → H2O (l)
Determining if it is an Acid or Base

How can you tell if something is acidic or
basic?

Use an electronic pH meter

Use an indicator such as
litmus

Use pH paper containing universal indicator
Acid/Bases Indicators
Using Table M

Litmus

pH range for color change



(4.5 – 8.3)
Color change: red to blue
Phenolphthalein

pH range for color change


(8 - 9)
Color change: colorless to
pink
What color would these be
if
pH = 10?
pH = 3?
Let’s Review
Based on the results of testing colorless solutions with
indicators, which solution is most acidic?
(1) a solution in which bromthymol blue is blue
(2) a solution in which bromcresol green is blue
(3) a solution in which phenolphthalein is pink
(4) a solution in which methyl orange is red

According to Reference Table M, what is
the color of the indicator methyl orange in a
solution that has a pH of 2?
(1) blue
(2) orange
(3) yellow
(4) red

Which indicator would best distinguish
between a solution with a pH of 3.5 and a
solution with a pH of 5.5?
(1) bromthymol blue
(2) litmus
(3) bromcresol green
(4) thymol blue

Which indicator is blue in a solution that
has a pH of 5.6?
(1) bromcresol green
(2) methyl orange
(3) bromthymol blue
(4) thymol blue

Which indicator is yellow in a solution with
a pH of 9.8?
(1) methyl orange
(2) bromcresol green
(3) bromthymol blue
(4) thymol blue

In which solution will thymol blue indicator
appear blue?
(1) 0.1 M CH3COOH
(2) 0.1 M HCl
(3) 0.1 M KOH
(4) 0.1 M H2SO4
Properties of Acids (Summary)

Produce H+ (as H3O+) ions in water

Electrolytes (conduct in solution)

Taste sour

pH is < 7

Corrode metals (see Table J)

React with bases to form salts and water
(Neutralization)
Properties of Bases (Summary)
Produce OH- ions in water
 Electrolytes (conduct in solution)
 Taste bitter, chalky
 pH is >7
 Feel soapy, slippery
 React with acids to form salts and water
(Neutralization)
Learning Check
Describe the solution in each of the following
as: 1) acid 2) base or 3)neutral.
A. ___soda
B. ___soap
C. ___coffee
D. ___ wine
E. ___ water
F. ___ grapefruit
53
Solution
Describe each solution as:
1) acid 2) base or 3) neutral.
A. _1_ soda
B. _2_ soap
C. _2_ coffee
D. _1_ wine
E. _3_ water
F. _1_ grapefruit
54
Learning Check
Identify each as characteristic of an
A) acid or B) base
____ 1. Sour taste
____ 2. Produces OH- in aqueous solutions
____ 3. Chalky taste
____ 4. Is an electrolyte
____ 5. Produces H+ in aqueous solutions
55
Solution
Identify each as a characteristic of an
A) acid or B) base
_A_ 1. Sour taste
_B_ 2. Produces OH- in aqueous solutions
_B_ 3. Chalky taste
A, B 4. Is an electrolyte
_A_ 5. Produces H+ in aqueous solutions
56