Chapter 17 (Exam 2)

Question 1

Acids (General Characteristics)

Answer 1

Sour taste, ability to dissolve many metals; ability to turn blue litmus paper red; neutralize bases

Question 2

Common Acids

Answer 2

• Hydrochloric (HCl) - Sulfuric (H2SO4) - Nitric (HNO3O) - Acetic (HC2H3O2) - Citric (H3C6H5O7) - Carbonic (H2CO3) - Hydrofluoric (HF) - Phosphoric (H3PO4)

Question 3

Carboxylic Acid

Answer 3

Contains: ((O)) H - O - C - R

Question 4

Bases (General Characteristics)

Answer 4

Bitter taste, slippery feel (react to oils to form soap-like substance); turn red litmus paper blue; ability to neutralize acids

Question 5

Alkaloids

Answer 5

Organic bases found in plants (often poisonous)

Question 6

Common Bases

Answer 6

• Sodium Hydroxide (NaOH) - Potassium hydroxide (KOH) - Sodium bicarbonate (NaHCO3) - Sodium carbonate (Na2CO3) - Ammonia (NH3)

Question 7

Arrhenius Definition: - Acid - Base - Acid + Base = ?

Answer 7

• Acid: Substance that produces H+ ions in aqueous solution –> H+ ions ALWAYS associate with H2O molecules to form hydronium ions (H3O+) –> Strong Acid: Completely ionizes in solution (weak: partially) - Bases: Substance that produces OH- ions in aqueous solution –> Strong Base: Completely dissociates in solution (weak: produces OH- by accepting proton from water/ionizing) - Acid + Base = Water

Question 8

Bronsted-Lowry Definition: - Acid - Base

Answer 8

• Acid: Proton (H+) donor - Base: Proton (H+) acceptor - Acids + Bases always occur together

Question 9

Amphoteric

Answer 9

Substances that can act as acids or bases

Question 10

Conjugate Acid/Conjugate Base

Answer 10

• Any base to which a proton has been added - Any acid from which a proton has been removed NH3 (base) + H2O (acid) –> NH4+ (conj. acid) + OH- (conj. base) - Base accepts proton and becomes conjugate acid - Acid donates proton and becomes conjugate base

Question 11

Binary Acids: Factors that Affect Ease of H+ Donated

Answer 11

• Factors influencing ease of H+ donated are polarity and strength - Increasing Electronegativity: Increasing Acidity Decreasing Strength: Increasing Acidity

Question 12

Oxyacids

Answer 12

• Contain H bonded to O atom H - O - H - Y (branch off in diff. directions) - Influence acidity: Electron of Y (increasing electronegativity = weakening polarizing H-O bond–more acidic) - Number of O atoms bonded to Y: Draw electron density away from element Y (more = stronger acid)

Question 13

Monoprotic Acid

Answer 13

Only one ionizable proton

Question 14

Diprotic Acid

Answer 14

• Two ionizable protons

Question 15

Strong Acids

Answer 15

• Hydrochloric (HCl) - Hydrobromic (HBr) - Hydroiodic (HI) - Nitric (HNO3) - Perchloric (HClO4) - Sulfuric (H2SO4) – Diprotic acid

Question 16

Weak Acids

Answer 16

• Hydrofluoric (HF) - Acetic (HC2H3O2) - Formic (HCHO2) - Sulfurous (H2SO3) - Carbonic (H2CO3) - Phosphoric (H3PO4)

Question 17

Generic Equilibrium Constant for Acid

Answer 17

HA (aq) + H2O –>/<– H3O+ + A-

HA (aq.) –>/<– H+ (aq) + A- (aq)

K_a = [H₃O⁺][A^-]/[HA]

K_a = [H⁺][A^-]/[HA]

Question 18

Water: Basicity and Acidity

Answer 18

• Water is amphoteric; when pure acts as an acid and a base itself

H₂O + H₂O –>/<–H₃O⁺ + OH^-

• K_w = [H⁺][OH^-]
• Acidic: [H₃O⁺] > [OH^-]
• Basic: [OH^-] < [H₃O⁺]
• K_w = 1.0 x 10^-14 at 25˚C

Question 19

Calculating pH

Answer 19

• log[H₃O⁺]
• [H₃O+][OH^-] = 1.0 x 10^-14

^{(then use negative log of hydronium ions)}

Question 20

Finding [H₃O⁺] and pH of Strong Acids

Answer 20

• Completely ionize, therefore concentration of H₃O⁺ = concentration of the stron gacid
• Then -log(H₃O⁺)

Question 21

Finding [H₃O⁺] and pH of Weak Acids

Answer 21

• Solve equilibrium problem
• Write out entirety of equation; solve ICE equilibrium problem
• Remember: HA (aq) + H₂O (aq) –>/<– H₃O⁺ (aq) + A^- (aq)
• Use x is small approximation; check and make sure that percentage is []

Question 22

Quadratic Equation

Answer 22

[- b +/- (b² - 4ac)^-2]/2a

from: ax² + bx + c

Question 23

Percent Ionization (Acids)

Answer 23

• Find concetration of hydronium ions
• Divide molarity of hydronium ions by initial molarity and multiply by 100%

Question 24

Trends in Acids

Answer 24

• Equilibrium H₃O⁺ concentration of weak acid increases with initial increasing concentration of acid
• Percent ionization of weak acid decreases with increasing concentration of acid

Question 25

Mixtures of Acids: Strong and Weak Finding pH and [H₃O⁺]

Answer 25

- Relative strength of acids allows us to neglect weaker acid and focus on strong one - Solve equilibrium for strong acid and the products of the reaction

Question 26

Mixtures of Acids: Weak + Weak Finding pH and [H₃O⁺]

Answer 26

- 3 potential sources of hydronium (two weak acids and water) - If K_a differs by factor of several 100s in magnitude, assume that weaker acid does not make contribution - Solve equilibrium equation with largest K_a initial and the products

Question 27

Common Strong Bases

Answer 27

- Lithium hydroxide (LiOH) - Sodium hydroxide (NaOH) - Potassium hydroxide (KOH) - Strontium hydroxide [Sr(OH)₂] - Barium hydroxide [Ba(OH)₂] --\> Mostly group 1A or 2A metal hydroxides ---\> 1A: Highly soluble and can form concentrated base solutions --\> 2A: Slightly soluble (dissocate in one step)

Question 28

Weak Bases/Common Weak Bases

Answer 28

- Produce OH- by accepting proton from H₂O; ionize H₂O to form OH- - Carbonate ion (CO₃^2-) - Methylamine (CH₃NH₂) - Ethylamine (C₂H₅NH₂) - Bicarbonate ion (HCO₃^-) - Pyridine (C₅H₅N) - Aniline (C₆H₅NH₂) --\> All are either ammonia or amines

Question 29

Weak Base Ionization Constant

Answer 29

- K_b: Extent of ionization of weak base; smaller the constant, weaker the base

Question 30

Finding OH- of Strong Base Solutions

Answer 30

- Concentration of OH- equals concentration of initial reactant; take -log(H3O+) to find pH (again, K_w = 1.0 x 10^-14)

Question 31

Finding OH- and pH for Weak Base Solution

Answer 31

- Write out equation, solve for ICE equilibrium problem - Use OH- x H3O+ = 1.0 x 10^-14 to find H3O+; then -log of hydronium!

Question 32

Anions as Weak Bases

Answer 32

- View as conjugate base of an acid - General: A- = conjugate base of HA - Anion that is a conjugate base of weak acid is itself a weak base - Anion that is conjugate base of strong acid is pH-neutral - Cl- = HCl - F- = HF - NO₃^- = HNO₃ - C₂H₃O₂ = HC₂H₃O₂

Question 33

K_w = ?

Answer 33

K_w = K_a x K_b pK_a + pK_b = 14

Question 34

Cations as Weak Acids

Answer 34

- In some cases, act as weak acids - Cations and counterions of strong bases typically pH neutral - NH₄⁺ (cation) = NH₃ (base) - C₂H₅NH₃⁺ = C₂H₅NH₂

Question 35

Small, Highly Charged Cations

Answer 35

- Smaller, more highly chared cation is, the more acidic its behavior

Question 36

Classifying Salt Solutions (4 Points)

Answer 36

1) Salts in which neither cation nor anion acts as and acid or base form pH-neutral solutions. 2) Salts in which cation does not act as an acid and anion acts as a base to form basic solutions. 3) Salts in which cation acts as an acid/anion does not act as a base forms acidic solutions. 4) Salts in which cation acts as an acid and anion acts as a base form solutions in which pH depends on relative strengths of acid/base

Question 37

Polyprotic Acids

Answer 37

- Require more than one step to ionize - K_a2 is always smaller for polyprotic acids (second proton must separate from an anion)

Question 38

Concentrations of Anions for Weak Diprotic Acid Solution (Concentration of X^2-?)

Answer 38

- General polyprotic (H₂X) (1) H₂X (aq) + H₂O (l) --\>/\<-- H₃O⁺ (aq) + HX^- (Ka₁) (2) HX^- (aq) + H₂O (l) --\>/\<-- H₃O⁺ (aq) + X^2- (aq) (Ka₂) Concentration X^2-: Use equlibrium constant and solve for X^2-

Question 39

Lewis Acids and Bases - Lewis Acid - Lewis Base

Answer 39

- Electron pair acceptor - Electron pair donor SUBSTANCE DOESN'T NEED TO CONTAIN H+ TO BE AN ACID - Molecules with incomplete octets act as acids - Some may reconfigure to act as Lewis Acids - Cations may act as Lewis acids as well....ugh.