19.1 Acid-Base Theories> 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights...

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)



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



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?



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



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)



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.



1.

Arrhenius acid = ________ base = ________

Bronsted-Lowry acid = ________ base = ________

Lewis acid = ________ base = ________

Conjugate acid-base pairs = __________________



1. Is acetic acid monoprotic, diprotic, or triprotic? Explain your answer!



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



ASSIGNMENTReview section 19.2 and

complete #s 18-24 due TODAY Wednesday 4-22



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




A. Acids

Acid Dissociation Constant - Ka

Write the Keq for the dissociation of CH3COOH(aq) above.

Keq =[H3O+] * [CH3COO-]

[CH3COOH] * [H2O]


(aq)




A. Acids

*** for dilute aqueous solutions the concentration of water is a constant so,

Ka = Keq * [H2O] =[H3O+] * [CH3COO-]

[CH3COOH]




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.




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.


(aq)




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




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




Bases

strong base = a base that dissociates completely into metal ions and hydroxide ions in aqueous solution

Examples: calcium hydroxide, magnesium hydroxide, sodium hydroxide




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)




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]




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]




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).




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



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



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?



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)



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?



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



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



page 684 #s 53 – 65

Due Tuesday day 3 4-28 both periods!

19.1 Acid-Base Theories> 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights...

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