Chapter 17 (Exam 2) Flashcards Preview

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1

Acids (General Characteristics)

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

2

Common Acids

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

3

Carboxylic Acid

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

4

Bases (General Characteristics)

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

5

Alkaloids

Organic bases found in plants (often poisonous)

6

Common Bases

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

7

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

- 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

8

Bronsted-Lowry Definition: - Acid - Base

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

9

Amphoteric

Substances that can act as acids or bases

10

Conjugate Acid/Conjugate Base

- 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

11

Binary Acids: Factors that Affect Ease of H+ Donated

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

12

Oxyacids

- 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)

13

Monoprotic Acid

Only one ionizable proton

14

Diprotic Acid

- Two ionizable protons

15

Strong Acids

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

16

Weak Acids

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

17

Generic Equilibrium Constant for Acid

HA (aq) + H2O -->/

HA (aq.) -->/

Ka = [H3O+][A-]/[HA]

Ka = [H+][A-]/[HA]

18

Water: Basicity and Acidity

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

H2O + H2O -->/3O+ + OH-

- Kw = [H+][OH-]

- Acidic: [H3O+] > [OH-]

- Basic: [OH-] < [H3O+]

- Kw = 1.0 x 10-14 at 25˚C

19

Calculating pH

- log[H3O+]

- [H3O+][OH-] = 1.0 x 10-14

(then use negative log of hydronium ions)

20

Finding [H3O+] and pH of Strong Acids

- Completely ionize, therefore concentration of H3O+ = concentration of the stron gacid

- Then -log(H3O+)

21

Finding [H3O+] and pH of Weak Acids

- Solve equilibrium problem 

- Write out entirety of equation; solve ICE equilibrium problem

- Remember: HA (aq) + H2O (aq) -->/3O+ (aq) + A(aq)

- Use x is small approximation; check and make sure that percentage is [ ]

22

Quadratic Equation

[- b +/- (b2 - 4ac)-2]/2a

from: ax2 + bx + c

23

Percent Ionization (Acids) 

- Find concetration of hydronium ions

- Divide molarity of hydronium ions by initial molarity and multiply by 100%

24

Trends in Acids

- Equilibrium H3O+ concentration of weak acid increases with initial increasing concentration of acid

- Percent ionization of weak acid decreases with increasing concentration of acid

25

Mixtures of Acids: Strong and Weak

Finding pH and [H3O+]

- 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

26

Mixtures of Acids: Weak + Weak

Finding pH and [H3O+]

- 3 potential sources of hydronium (two weak acids and water)

- If Ka differs by factor of several 100s in magnitude, assume that weaker acid does not make contribution

- Solve equilibrium equation with largest Ka initial and the products

27

Common Strong Bases

- 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)

28

Weak Bases/Common Weak Bases

- Produce OH- by accepting proton from H2O; ionize H2O to form OH-

- Carbonate ion (CO32-)

- Methylamine (CH3NH2)

- Ethylamine (C2H5NH2)

- Bicarbonate ion (HCO3-)

- Pyridine (C5H5N)

- Aniline (C6H5NH2)

--> All are either ammonia or amines 

29

Weak Base Ionization Constant

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

30

Finding OH- of Strong Base Solutions

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