Acids and Bases 3
Boon Chemistry January 17 & 18, 2013
Catalyst
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Take out your homework
please.
Label the acid, base, conjugate
acid and conjugate base in the
following reaction. Draw an
arrow showing the movement
of a proton from the acid to
base.
H2CO3 + NH3  HCO3- + NH4+
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Objectives
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I can explain the relationship between
pH and H3O+ concentration.
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I can categorize acids and bases using
the pH scale.
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Agenda
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Use the definition of acid, base,
and conjugate acid and base to
justify your answers.
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Catalyst and Homework Review
pH scale Foldable and White
Board Practice
Practice: pH WS
Exit Slip: pH and strong/weak
acid/base
Exit Slip: Answers Standard 5a
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The neutralization of any strong acid and strong base produces
mostly
(a) H2O molecules
(c) H3O+ and OH- ions
(b) H3O+ ions
(d) OH- ions
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Why? Example: NaOH + HCl  NaCl + H2O
 This was the catalyst Wednesday.
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A property listed below that is not characteristic of an acid is
(a) a sour taste.
(c) the ability to conduct an electric
current.
(b) a slippery feel. (d) reactivity with metals.
Why? This is a property of a base. This is in your notes.
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Exit Slip answers continued
Both acids and bases are electrolytes. This means…
(a) they are the main ingredients in sports drinks.
(b) they produce electricity and will shock you.
(c) they conduct electricity when dissolved in water.
(d) none of the above.
Why? This is the definition of electrolyte.
List two examples of acids and two examples of bases that we may
find at home.
Acids: lemons, tomatoes, coffee, orange juice, stomach acid, etc
Bases: soap, cleaning products with ammonia, baking soda, antacid,
drain cleaner etc.
Exit Slip Review Standard 5b
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Pure ammonia that is not in aqueous solution does not form
hydroxide ions. Why is pure ammonia considered a base using
the BrØnsted-Lowry definition?
(a) The ammonia molecule accepts protons from other
molecules.
(b) The ammonia molecule donates protons to other molecules.
(c) The ammonia molecule reacts with sulfuric acid.
(d) The ammonia molecule donates a hydroxide group to other
molecules.
Why? Bases are proton acceptors. They gain or take a proton.
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A substance that produces hydrogen ions (H+) when dissolved in
water is classified as
(a) an acid.
(c) a salt.
(b) a base.
(d) an electrolyte.
Why? Acids are proton (H+) donors or givers or producers.
Exit Slip Review Continued
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In the reaction H3O+ + CO32– → HCO3– + H2O, which
compound acts as the base?
(a) H3O+
(c) HCO3–
(b) CO32–
(d) H2O
Why? This compound takes a H+ from the H3O+ to form
HCO3– . Substances that take protons are bases.
The conjugate acid of the chloride ion, Cl-, is
(a) Cl2
(c) H+
(b) HCl
(d) ClO
Why? A conjugate acid is formed by adding a proton (H+).
Cl- + H+ → HCl
Homework Review page 566 #1, 4, 5, 18, 19,
21
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1. A strong acid dissociates completely in solution. A
weak acid dissociates only to a small extent in solution.
(See pp. 532)
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4. The ammonium ion NH4+ is the conjugate acid to the
base ammonia (NH3). (See pp. 537.)
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5. Water is considered amphoteric because it can act
either as an acid, donating a proton, or as a base,
accepting a proton. (See pp. 534 for examples of water
acting as a base and pp. 536 for examples of water acting
as an acid.)
Homework Review pp. 538 # 1, 3, 5, 6, 7, 9,
13
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18. Weak acids and weak bases are poor electrical conductors
or electrolytes because they do not fully dissociate in solution.
Therefore, there are not many ions in solution that will
conduct electricity. (See pp. 531-532, 534.)
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19. The strength of an acid is a measure of whether or not the
acid fully dissociates in solution. Strong acids fully dissociate
and weak acids do not. The concentration of an acid is a
measure of the amount of acid in a certain volume of solution.
(See pp. 532 and notes on concentration.)
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21.
HCN + H2O 
CN- + H3O+
acid
base
conjugate conjugate
base
acid
pH Foldable
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The pH scale: pH is a value used to express the acidity
or alkalinity of a solution.
pH stands for “power of hydrogen.”
The pH scale is a negative
logarithmic scale.
Alkaline
This means that a low
pH reflects
means
base. a high hydronium ion
concentration.
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How does pH and [H3O+] relate to pOH and [OH]?
When the concentration of hydronium ions increases, the
concentration of hydroxide ions decreases.
In fact, if we know the pH or the [H3O+] of a solution, we
can determine the pOH and the [OH-]. Here’s how:
pH + pOH = 14
[OH-][H3O+] = 10-14
pH + pOH = 14
More
Acidic
[OH-][H3O+] = 10-14
More
Basic
1. The color of a solution identifies if it is an
acid, base, or neutral solution.
A.
True B. False C. Pink are base and clear are acid
2. Which solution is basic?
A
B
D. More than one
C
E. None
3. Which solution is acidic?
A
B
C
D. More than one
E. Difficult to tell
4. Which solution is basic?
A
B
D. More than one
C
E. None
5. Which solution is acidic?
A
B
D. More than one
C
E. None
6. How will adding water effect the pH?
Increase the pH
B. Decrease the pH
C. No pH change
A.
A: more water
lessens the
acidity, so pH
goes up
7. How will equal
amount of water effect
the pH?
A.
B.
C.
D.
Increase the pH
Decrease the pH
The pH will be cut
in half
No pH change
B: more water
lessens the basicity
, so pH goes down,
from 10 to 9.7,
but not by 2 (log
scale)
8. What is the order from most acidic to
most basic?
A
A. A B C
B. A C B
C.B A C
D.C B A
E. C A B
B
C
9. What is the order from most acidic to
most basic?
A. A B C
B. A C B
C.B A C
D.C B A
E. C A B
A
B
C
pH Foldable: Back Left of WS
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Calculate pH from [H3O+]
pH = -log [H3O+]
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Ex: What is the pH of a 0.0001 M HCl solution?
Step 1: Convert to scientific notation
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0.0001 = 1.0 x 10-4
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Step 2: Use the pH equation and your pH scale
pH = -log [1.0 x 10-4]
= - (-4)
=4
pH Foldable: Back Middle of WS
Calculate pH from pOH
pH + pOH = 14
Ex: What is the pH of a solution of ammonia with a pOH of
5?
Step 1: plug the given into the equation.
pH + 5 = 14
Step 2: Solve for the unknown
pH + 5 = 14
pH + 5 -5 = 14 -5
pH = 9
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pH Foldable: Back Right of WS
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Calculate [H3O+] from pH
[H3O+] = 10-pH
Ex: What is the hydronium ion concentration of a solution
with a pH of 3?
Step 1: plug the given into the equation.
[H3O+] = 10-3
Step 2: Convert to scientific notation.
10-3 = 1.0 x 10-3
Independent Work Time
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Expectations:
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You may work on the following:
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You must work at your seat. You may speak quietly to the
students next to you.
Raise your hand if you need help.
You may get up to check your answers.
pH foldable worksheet
pH and pOH worksheet
Any other Acid/Base WS or HW
Use pp. 530547 for help!
Answers are posted at the front of the class.
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Correct your work.
Exit Slip
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Expectations:
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Tools:
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You may use all your notes, worksheets, and flash cards.
You may use your own calculator.
What do I turn in?
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You will work silently and independently.
When you are done, cover your exit slip with your handouts.
You will turn in your exit slip only.
Homework:
 Read pp. 539-547 pp.547 #1-5, pp. 567 # 24, 25, 26
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Complete any worksheets or article questions that you have
not finished.
Homework
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Due Next Class: Read pp. 539-547 pp.547 #1-5, pp. 567 #
24, 25, 26
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Due Next Thursday/Friday: Complete any worksheets or
article questions that you have not finished.
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Practice your vocabulary with flashcards!