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Name: _____________ Period: _______
Acids and Bases
March 25
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Acids and Bases
Unit Begins
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Apr 1
4
5
Acids and Bases
Unit Ends
Unit Test
Packet & Homework
Due
6
Review
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Review
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3rd Quarter Ends
End of Quarter test
La Habra High Spring Break! YEAH!!!!
5. Acids, bases, and salts are three classes of compounds that form ions in water solutions. As a
basis for understanding this concept:
a. Students know the observable properties of acids, bases, and salt solutions.
b. Students know acids are hydrogen-ion-donating and bases are hydrogen-ion-accepting
substances.
c. Students know strong acids and bases fully dissociate and weak acids and bases partially
dissociate.
d. Students know how to use the pH scale to characterize acid and base solutions.
e. * Students know the Arrhenius, Brønsted-Lowry, and Lewis acid–base definitions.
f. * Students know how to calculate pH from the hydrogen-ion concentration.
Math Review: Logarithms
N = 10x
log N = x
N = antilog x
Practice 1: Use your calculator, find out the following logarithms:
a) 10-3, b) 2.0 x 10-5, c) 0.0056, d) 5000, e) 3.8 x 109
Practice 2: Use your calculator, find out the following values:
a) 0.50, b) -3.00, c) 2.5, d) -7.9
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Acid Base Comparison Table
Acid
Base
Properties
Sour taste
Give sharp stinging pain in a cut or
wound.
Corrosive – burns skin
Bitter taste
Slippery feel
Corrosive – cause deep,
painful, slow-healing wound
Indicator
Acid Solution
Neutral Solution
Basic Solution
Litmus
Bromothymol Blue
Phenolphthalein
Universal Indicator
red
yellow
clear
red
purple
blue
clear
yellow-green
blue
blue
purple
purple
pH Scale
Examples
Common Acid
Hydrochloric acid
Sulphuric acid
Stomach juice
Lemons
Vinegar
Apples
Oranges
Grapes
Sour milk
White bread
Fresh milk
pH
0.1
0.3
1-3
2.3
2.9
3.1
3.5
4
4.4
5.5
6.5
Common Bases
Human saliva
Distilled water
Blood plasma
Eggs
Seawater
Borax
Milk of magnesia
Ammonia water
Limewater
Caustic soda
pH
6-8
7
7.4
7.8
7.9
9.2
10.5
11.6
12.4
14
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Theory
Arrhenius
Arrhenius acid – any compound
when mixed in solution that will
give off H+ ions
Arrhenium base – any
compound when mixed in
solution that will give off OHions
Brønsted-Lowry
Bronsted-Lowry acid – any
compound when mixed in
solution which donates or gives
up a proton (H+)
Acid
H+ producer
Base
OH- producer
Example: HCl→H+ + Cl-
Example:
NaOH→Na+ + OHHighly solubility in water
NaOH – lye, drain opener, Easy
Off
KOH
Acids that contains x
ionizable hydrogens. Only
the hydrogens in very polar
bonds are ionizable.
Monoprotic acids HNO3,
CH3COOH
Diprotic acids H2SO4
Triprotic Acids H3PO4
Low solubility in water
Ca(OH)2 – 0.165g
Mg(OH)2 – 0.0009g – milk of
magnesia, antacid
+
H donor
H+ acceptor
Example: 1) H2O, 2) HCl
Example:1) NH3, 2) H2O
+
1) NH3(aq) + H2O(l) ↔NH4 (aq) + OH-(aq)
2) HCl(g) + H2O(l) ↔ H3O+(aq) + Cl-(aq)
Bronsted-Lowry base – any
compound when mixed in
3) HCO3-(l)+ H2O(l) ↔ H3O+(aq) + CO3-2 (aq)
solution which accepts or takes a
proton (H+)
Amphoteric: a substance which may serve as either an acid or
a base. H2O is an example of an amphoteric substance because
Conjugate acid – formed on the it may either donate its H+ or accept an H+ from another
product side of a reaction from
substance.
the base of the reactants side;
Conjugate Acid-Base Pairs
formed when the base accepts
Acid
Base
the proton
HCl
Cl
HSO4Conjugate base – formed on the H2SO4
H3O+
H2O
product side of a reaction from
HSO4
SO4-2
the acid of the reactants side;
formed when the acid donates its CH3COOH
CH3COOproton
H2CO3
HCO3HCO3CO3-2
NH4+
NH3
H2O
OH-
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Lewis
electron-pair acceptor
electron-pair donor
Lewis Acid: a substance that can
accept a pair of electrons to
form a covalent bond
Lewis Base: a substance that can
donate a pair of electrons to
form a covalent bond
Problem 1. Identify the Lewis acid and Lewis base in each reaction:
a)
H+ + H2O → H3O+
b)
AlCl3 + Cl- → AlCl4-
Hydrogen Ions from Water
Self-ionization:
H+ always joins with a water molecule:
For aqueous solutions, the ion-product constant for water (Kw)
Kw = [H+] x [OH-] = 1.0 x 10-14
Problem 2. Colas are slight acidic. If the [H+] in a solution is 1.0 x 10-5M, is the solution acidic, basic or
neutral? What is the [OH-] of this solution?
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Calculating pH and pOH
pH scale – a scale from 0 – 14, which measures whether a substance is acidic or basic. 7 is a neutral pH,
below 7 is acidic, and above 7 is basic. The father away from 7, the acid or base is the stronger the
substance is. (Refer to the pH scale on page 2)
pH – measure of “parts Hydrogen”; measures the strength of an acid or a base by measuring the
concentration of the hydrogen ion in solution
pOH – measure of “parts Hydroxide”
indicator – a substance which can measure whether a substance is an acid or base; usually involves a
color change
Formula
Ion concentration
pH
pH = -log[H+]
[H+] = antilog pH
[H+] is the molarity of hydrogen ion
pH = 14 - pOH
pOH
pOH = -log[OH-]
[OH-] = antilog pOH
[OH-] is the molarity of hydroxide ion
pOH = 14 - pH
pH + pOH = 14
Problem 3. What is the pH of a solution with a hydrogen-ion concentration of 4.2 x 10-10M?
Problem 4. The pH of an unknown solution is 6.35. What is its hydrogen-ion concentration?
Problem 5. What is the pH of a solution if [OH-] = 4.0 x 10-11 M?
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Strong Acids/Bases: compounds which dissociate (break up into ions) completely or to a great extent
when placed in solution
Weak Acids/Bases: compounds which dissociate (break up into ions) very little, poorly in solution
Relative Strengths of Common Acids and Bases
Problem 6. Which acid in the above table would you expect to have the lowest degree of dissociation?
Which base would have the lowest degree of dissociation?
Neutralization Reaction: the type of reaction found in acid/base chemistry; occurs when an acid reacts
with a base forming neutral compounds such as salt and water.
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l)
Problem 7. What are the products of a reaction between an acid and a base?
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Name: ________________ Period: _______
Acids and Bases Classwork
True or False
____
1.
Hydrochloric acid is a strong acid that is diprotic.
____
2.
A Bronsted-Lowry base is a hydrogen-ion acceptor.
____
3.
A compound can act as both an acid and a base.
____
4.
If the [H+] in a solution increases, the [OH-] must decrease.
____
5.
The [OH-] is less than 10-7M in a basic solution
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6.
Acids are completely dissociated in aqueous solution.
____
7.
The reaction of an acid and a base produces only water.
Matching
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Lewis base
a.
acids that contain three ionizable hydrogens
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9.
hydronium ion (h3o+)
b.
aqueous solution in which [h+] and [oh-] are equal
____ 10. triprotic acids
c.
bases that do not dissociate completely in aqueous
solution
____ 11. conjugate base
d.
solution in which [h+] is greater than [oh-]
____ 12. neutral solution
e.
an electron-pair donor
____ 13. acid solution
f.
particles that remains when an acid has donated a
hydrogen ion
____ 14. strong acids
g.
a water molecule that gains a hydrogen ion
____ 15. weak base
h.
acids that ionize completely in aqueous solution
Multiple Choice
____ 15. The pH of a sample of orange juice is 3.5. A sample of tomato juice has a pH of 4.5.
Compared to the [H+] of orange juice, the [H+] is
a. 1.0 times higher
b. 10 time lower
c. 10 times higher
d. 1.0 time lower
____ 14. Which species is the conjugate base of an ammonium ion, NH4+?
a. H2O
____
b. OH-
c. NH3
d. H3O+
15. A solution with a hydrogen ion concentration of 2.3 x 10-8M has a pH between
a. 2 and 3
b. 3 and 4
c. 7 and 8
d. 8 and 9
7
____
16. The net ionic equation for the neutralization reaction between solutions of potassium
hydroxide and hydrochloric acid is:
a. H+(aq) + OH-(aq) → H2O(l)
b. KOH(aq) + HCl(aq) → H2O(l) + KCl(aq)
c. K+(aq) + Cl-(aq) → KCl(aq)
d. K+(aq) + OH-(aq) + H+(aq) + Cl-(aq) → KCl(aq) + H2O(l)
____
17. What are the concentrations of H+ and OH- in pure water at 25ºC?
a. 1.0 x 10-5 and 1.0 x 10-7
b. 1.0 x 10-7 and 1.0 x 10-5
c. 1.0 x 10+7 and 1.0 x 10-7
d. 1.0 x 10-7 and 1.0 x 10-7
Calculations, etc. Show work:
18. Calculate the pH for the following solutions and indicate whether each solution is acidic or
basic. (Circle one)
a. [H+] = 1 x 10-2M
Acid/Base
pH =
b. [OH-] = 1 x 10-2M
Acid/Base
[H+] =
pH =
-
c. [OH ] = 1 x 10-8M
Acid/Base
[H+] =
pH =
19.
What are the hydroxide-ion concentrations for solutions with the following pH/pOH values?
Are they acidic or basic? Circle the appropriate ones.
a. pH = 4.00
[H+] =
Acid/Base
b. pOH = 8.50
pH =
Acid/Base
[H+] =
c. pH = 11.2
Acid/Base
[H+] =
20. Write the formula for the conjugate base of each acid.
a. H2SO4
b. HCN
21. Write the formula and name of the conjugate acid of each Bronsted-Lowry acid.
a. ClO2-1
b. H2PO4-1
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