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19.1 Acid-Base Theories>19.1 Acid-Base Theories>
1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
LAB:
COMPLETE EQUATION:
KSCN(aq) + FeCl3(aq) KCl(aq) + FeSCNCl2(aq)
EQUILIBRIUM BETWEEN IONS:
Fe+3(aq) + SCN-1
(aq) FeSCN+2(aq)
(orange) (clear) (red)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
2 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
1. Test Unit 8 = ___%
2. I prepared by…
3. Next time I will prepare by…
4. Set a goal for next time. Goal = ____
If you met your goal you must improve by
at least one point. If not it stays the
same.
4-22 day 5
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
3 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
II. Hydrogen Ions and Acidity (notes page 4):
B. pH:
Example problem:What is the pH of a solution if [OH-] = 4.0 * 10-11 M?
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
4 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
C. Measuring pH:
acid-base indicators or ___________ can be used to measure pH.
acid-base indicators = ______________________ ________________________________________________________________________________________
review figure 19.8 on page 660.
pH meter = ________________________________ ____________________________________________
pH meters
an acid-base indicatordissociates in a known pH range and its acid form and base form are different colors
used to make rapid, continuous measurements of pH
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
5 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases Acids and bases are classified as strong or weak
depending on the degree to which they ionize in water.
A. Acids
strong acid = an acid that completely ionizes in aqueous solution
Examples: hydrochloric acid, sulfuric acid, nitric acid
HCl(g) + H2O(l) H3O+(aq) + Cl-
(aq)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
6 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
A. Acids
weak acid = an acid that slightly ionizes in aqueous solution
Examples: acetic acid, carbonic acid
CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-
(aq)
Review table 19.6 on page 664.
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
7 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
1.
Arrhenius acid = ________ base = ________
Bronsted-Lowry acid = ________ base = ________
Lewis acid = ________ base = ________
Conjugate acid-base pairs = __________________
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
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1. Is acetic acid monoprotic, diprotic, or triprotic? Explain your answer!
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
9 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Diprotic acid
Sulfuric acid
Kw
pH
Alkaline
Lewis acid
1 X 10-14
Arrhenius base
Acetic acid
H+ concentration
Conjugate acid-base pair
Hydrochloric acid
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
10 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
ASSIGNMENTReview section 19.2 and
complete #s 18-24 due TODAY Wednesday 4-22
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
11 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
Define acid in your own words.
Day 6 4-23
Arrhenius acid = an acid that gives hydrogen ions
Bronsted-Lowry acid = hydrogen ion donor
Lewis acid = an acid that accepts a pair of electrons
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
12 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
A. Acids
Acid Dissociation Constant - Ka
Write the Keq for the dissociation of CH3COOH(aq) above.
Keq =[H3O+] * [CH3COO-]
[CH3COOH] * [H2O]
CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-
(aq)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
13 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
A. Acids
*** for dilute aqueous solutions the concentration of water is a constant so,
Ka = Keq * [H2O] =[H3O+] * [CH3COO-]
[CH3COOH]
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
14 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
A. Acids
the acid dissociation constant (Ka) measures the extent to which an acid dissociates in aqueous solution, and so can be used to represent the strength of an acid. The stronger the acid, the higher the Ka value.
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
15 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
A. Acids
Example Calculation:At equilibrium a solution of acetic acid has the following concentrations: [CH3COOH] = 0.0987M, and [H3O+] = [CH3COO-] = 1.34 * 10-3M. Find Ka.
CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-
(aq)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
16 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Additional Example Calculation:In a 0.200 M solution of a monoprotic weak acid, [H+] = 9.86 * 10-4 M. What isthe Ka for this acid?
Ka = 4.89e-6
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
17 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Additional Example Calculation:In a 0.1 M solution of methanoic acid [H+] = 4.2e-3 M. Calculate the Ka of this acid. Methanoic acid is a weak monoprotic acid.
Ka = 1.84 e-4
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
18 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Bases
strong base = a base that dissociates completely into metal ions and hydroxide ions in aqueous solution
Examples: calcium hydroxide, magnesium hydroxide, sodium hydroxide
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
19 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Bases
weak base = a base that reacts with water to form the conjugate acid of the base and hydroxide ions – amount of dissociation is relatively small
Examples:
NH3(aq) + H2O(l) NH4+
(aq) + OH-(aq)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
20 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Base Dissociation Constant – Kb
Write the Keq for the dissociation of NH3(aq) above.
*** for dilute aqueous solutions the concentration of water is a constant so,
Keq =[NH4
+] * [OH-]
[NH3] * [H2O]
Kb = Keq * [H2O] =[NH4
+] * [OH-]
[NH3]
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
21 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Base Dissociation Constant – Kb
Or in general form:
the base dissociation constant (Kb) measures the extent to which a base dissociates in aqueous solution, and so can be used to represent the strengthof a base. The stronger the base, the higher the Kb value.
Kb =[conjugate acid] * [OH-]
[base]
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
22 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Differentiating Concentration and Strength:
Strength refers to the extent of ionization or dissociation of an acid or base, while concentration indicates how much of a substance is dissolved. Recall that substances can dissolve without dissociating (sugar).
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
23 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
III. Strong and Weak Acids and Bases
Differentiating Concentration and Strength:
*** Strength is independent of concentration and vice versa.
Acidic Solution
Molar Concentration
Relative Concentration
Relative Strength
Hydrochloric acid
12 M HCl Concentrated Strong
Gastric Juice (stomach acid)
0.08 M HCl Dilute Strong
Acetic acid 17 M CH3COOH Concentrated Weak
Vinegar 0.2 M CH3COOH Dilute Weak
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
24 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
http://wps.prenhall.com/esm_brown_chemistry_9/2/660/169060.cw/index.html
Homework # 1 Chapter 16 – show me successful screen (100%) OR email to me
Pd 3 Day 6
4-23
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
25 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
1. What are amphoteric substances? Example =
Day 1 4-24
2. If the [H+] in a solution is 1.0 * 10-6 M, is the solution acidic, basic, or neutral?
What is the [OH-] of this solution?
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
26 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
IV. Neutralization Reactions
Acid-Base Reactions = Neutralization Reactions
In general acids and bases react to produce a salt (ionic substance) and water.
The complete reaction of a strong acid and a strong base produces a neutral solution – neutralization reaction.
Example: HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
27 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
IV. Neutralization Reactions
Acid-Base Reactions = Neutralization Reactions
Mole Ratios and Neutralization Reactions (example problem)
How many moles of sulfuric acid are needed to neutralize 0.50 moles of sodium hydroxide?
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
28 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
1. What is the pH of a solution with a hydrogen-ion concentration of 3.3 * 10-6 M?
2. What is the hydroxide ion concentration for a solution with a pH of 3.00?
3. What is the pH of solution with a [H+] of 4.2 * 10-5?
5.48
1.0 * 10-11
4.38
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
29 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
http://wps.prenhall.com/esm_brown_chemistry_9/2/660/169060.cw/index.html
Homework # 1 Chapter 16 – show me successful screen (100%) OR email to me
Pd 3 Day 6
4-23Pd 1 4-
24
19.1 Acid-Base Theories>19.1 Acid-Base Theories>
30 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.
page 684 #s 53 – 65
Due Tuesday day 3 4-28 both periods!