Acids & Bases
chapter15
6 acids
Sulfuric
Nitric
Hydrochloric
Phosphoric
Carbonic
Acetic Acid
H2SO4
HNO3
HCl
H3PO4 …cola
H2CO3
HC2H3O2 …vinegar
What do you notice?
What makes an acid an acid?
H+
HCl + H20
Acids …
ionize themselves…
+
Cl-
break apart into their ions.
Remember water is very polar
H30+ + Cl-
H20 + HCl
You may see…either…..
These have names:
hydronium ion,
ion.
H30+ or
, hydrogen ion,
H+
, proton
Bases
Sodium Hydroxide
Magnesium Hydroxide
Aluminum Hydroxide
Ammonia
Sodium Hydrogen Carbonate
NaOH
Mg(OH)2
Al(OH)3
NH3
NaHCO3
What do you notice?
What makes a base a base? (OH) or the ability to make an (OH)
Base solutions are sometimes called ALKALINE SOLUTIONS
Bases dissociate ….. Break apart producing hydroxide
NaOH + H20
NH3 + H20
Na+ +
NH4+ +
OHOH-
Strong vs. Weak
Can tell 2 ways
HX + H20
p.460 & p. 469
memorize them
arrows
H30+ + X-
label
Strong acids:
Weak acids:
HCl, H2SO4, HNO3
Strong Base:
Weak base:
group 1 or 2 metal hydroxides
NH3
dissociates completely
ionize completely
H2CO3, HC2H3O2, H3PO4
HF + H20
H2SO4 + H20
F- + H30+
HSO4 + H30+
Strength of acids
depends on:
H+ production
polarity of bonds
ionization
The greater the polarity of bond = greater strength
The greater the ionization = greater strength
Strong acids= HCl, HNO3, H2SO4
Weak Acid = H3PO4, H2CO3, HC2H3O2
Notice: strength of acid does not depend on number of hydrogens
Strength of bases
depends on:
OH- production
polarity of bonds
dissociation of hydroxide
The greater the polarity of bond = greater strength
The greater the dissociation = greater strength
Base solutions are sometimes called
alkaline solutions
Strong Bases: NaOH, KOH, Ca(OH)2, Ba(OH)2
Weak Base: NH3
Note: Alkali metals are stronger than alkaline earth….why?
Strong Acid/ Strong Base = Strong electrolyte……..why?
pH Scale
pH measures [concentration] of H30+ or OHpH ….. O – 14
0
3
7
10
14
Units of 10
4.6 pH is 10x stronger than 5.6pH
4.6 pH has 10x [H30] than 5.6 pH
Pure water is neutral…..pH 7
“self-ionization of water
Water produces ½ H+ and ½ OH-
[H+]
[OH-]
20 minute lab
Red litmus paper turns blue in base
Blue litmus paper stays blue in base
Determine pH using the rainbow chart
pH = [H30+] or [H+]
pH = power of the Hydrogen
Calculating pH from concentrations
pH = -log [H3O+]
pOH = -log [OH-]
pH + pOH = 14
ws.17.24
Yellow
Calculator
(-)
log
number
2nd
EE
exponent
Find pH of a solution of hydronium concentration of [3 x 10-5]?
pH = -log [3 x 10-5]
(-)
log
3
Yellow
EE
2nd
-5
=
[1 x 10-3 M] HCl
[1 x 10-5 M] HNO3
[0.001 M ] HCl
[0.09 M ] HBr
[1.34 x 10-4M] HCl
[7.98 x 10-2 M] HNO3
Calculate pH
pH + pOH = 14
ph
2
pOH
8
6
13
4
7
=14
=14
=14
=14
=14
=14
Find the pH of a solution of Hydroxide
concentration of [3 x 10-5]
(-)log 3
Yellow
2nd
EE
-5 =
BUT it is hydroxide so…..it is the pOH….so
subtract it from 14.
Calculate pH
[1 x 10-4 M] NaOH
[1 x 10-3 M] KOH
[1 x 10-6 M] LiOH
[3.2 x 10-2 M] Mg(OH)2
[0.08 M] Ca(OH)2
Calculate pH
Hydronium concentration of [.001M]
Hydroxide concentration of [.001 M]
H+ concentration of [ 1 x 10-5 M]
OH concentration of [1 x 10-5 M]
Ws.14.1
Ws.17.26
1.
A popular soda pop drink is measured to have a hydronium
concentration of 1.34 x 10-4. What is the pH and is it acidic,
base or neutral?
2.
The molarity of hydroxides in a pancake syrup is
1.0 x 10-8M. Pancake syrup by law must have a pH lower
than 7 to be sold in the open market. Calculate the pH and
identify if acid, base, neutral. Can it be sold?
3.
You work for Colgate Toothpaste. You need to make
stannic fluoride solution of hydroxide molarity [2.44 x 10-4].
What is the ph? Is it acid, base, neutral?
If pH is 7.40 what is the [hydronium] or the molarity?
Yellow
2nd
log
“If given pH…find antilog”
negative #
= [hydronium conc.]
-7.40
= [.00000004] or [4 x 10-8]
“secret….hydronium concentration is the molarity ”
BUT::::: if they also ask for hydroxide concentration one must use the
equilibrium constant for water:::::::::
Equilibrium Constant for water is
Kw = [H+] [OH-]
Kw = [1 x 10-7] [1 x 10-7]
Kw = 1 x 10-14
1.
The pH of an orange is 4.0pH. What are the [H30] and
[OH] in this fruit? What is its Molarity?
2.
Lemons have a pH 3.15. What are the hydronium and
the hydroxide concentrations? What is its molarity?
3.
What is the molarity of pH is 12.9 for a Calcium
hydroxide solution?
Remember: 3 formulas:
Remember:
Remember:
Remember:
Remember:
pH=-log[H3O]
pOH=-log[OH]
pH + pOH = 14
[H3O] is hydronium concentration
or…..molarity for an Acid
or…..H+ proton concentration
[OH] is hydroxide concentration
or molarity for a base
if given pH use antilog to calculate [H3O] [OH]
put pH in as negative number
Kw = [H3O] [OH] = 1x10-14
Kw = [1x10-7] [1x 10-7]
Kw = 1x10-14
Neutralization Reaction
p.474
Strong acid + Strong Base
salt + water
Look on reference table: 4c
HCl + H20
NaOH + H20
H+ + ClOH- + Na+
Put them together
HCl + NaOH
NaCl + H2O
Salt: a compound composed of
a cation+ from an base
and an anion- from a acid.
Stomach Ache
CaCO3 ….tums
HCl
+
Mg(OH)2 …milk of magnesia
NaCO3 …. Rolaids
Neutralize …………..salt + H20
HCl + CaCO3
CaCl + CO2 + H20
HCl + Mg(OH)2
MgCl + H20
HCl + NaCO3
NaCl + CO2 + H2O
Which will make you burp?
Tums and Rolaids… that is why old people prefer milk of magnesia
Titration:
the controlled addition and measurement of
the amount of a solution of known concentration
required to react completely with a
measured amount of a solution of unknown concentration
p.497
Equivalence point:
The point at which the two solutions
used in a titration are present in chemically equivalent amounts
p. 498
Indicator:
an organic substance that changes color whether in
acid or base…….Phenolphthalein
Calculating Titration Problems ws 19-3
On your reference sheet
nM1V1 = nM2V2
n = # of (H) or (OH) in the molecule
Ws 19-3
1. A volume of 30mL of 0.25M HCl neutralizes a 50mL
sample of KOH solution. What is the concentration of
KOH?
Create new copyrght
6. A volume of 50mL of 0.30M HCl
neutralizes a 60mL sample Ca(OH)2
solution. What is the concentration of
Ca(OH)2?
2 acid / base theories
Arrhenius acids & bases
p. 459
Arrhenius acid = a chemical that increases H+ ions.
Arrhenius base = a chemical that increases OH- ions
“limited because must be in water….not everything in water..p.464”
Bronsted-Lowery acids & bases p.464
Bronsted-Lowery acid = a chemical that is a proton donor (H+)
Bronsted-Lowery base = a chemical that is a proton acceptor (H+)
“ notice no mention of OH”
Conjugate acid/ base
the species that forms in result of gaining or losing a proton (H+)
Arrhenius
Bronsted-Lowery
Overhead worksheet 15.2,3,, 15.4
acid
base
H+donor
H+donor
OH- producer
H+ acceptor
Overhead 88 , 87 quick lab
Remember Equilibrium
Keq = [conc] [conc]
….(g) and (aq) but not liquids nor solids
Equilibrium Constant for water is
Kw = [H+] [OH-]
Kw = [1 x 10-7] [1 x 10-7]
Kw = 1 x 10-14
On chemistry table….constant like..
pie = 3.14
r = .0821
We can use this constant
(Kw = 1 x 10-14) to calculate pH of a solution
Ws problems 17.