Acids & Bases & Oxidation-Reduction Reactions

Question 1

What are the two main theories on acids and bases?

Answer 1

• Arrhenius theory of acids & bases

- bronsted-lowry theory

Question 2

What is the Arrhenius theory of acids and bases?

Answer 2

• acid: substance, when dissolved in water, dissociates to produce hydrogen ions
  
  • hydrogenion: H+ also called “proton”
  • but Arrhenius not explain observation of protons do not exist as H+ in aq solutions, rather they interact W/ water to form hydronium ions H3O+
• base: substance, when dissolved in water, dissociates to produce hydroxide ions OH-

Question 3

What is the bronsted-lowery theory?

Answer 3

• acid: proton (H+) donor

- base: proton (H+) acceptor

Question 4

What are the acid-base properties of water?

Answer 4

• Water possesses both acid and base properties aka amphiprotic
• water used most commonly used as solvent for both acids & bases
• solute-solvent interactions btwn-water & both acids & bases promote solubility & dissociation

Question 5

What are conjugate acids and bases?

Answer 5

HX + Y (reversible arrows) X- + HY+

• Conjugate acid: what base becomes after it accepts a proton
  
  • > HY+ is conjugate acid of baseY
• Conjugate base: what acid becomes after it donates its proton
  
  • > X- is conjugate base of acid HX
• Conjugate acid -base pair: acid & base on opposite sides of equation
  
  • > HY+ & Y
  • > HX & X-

Question 6

What is acid & base strength based off of?

Answer 6

• based on degree of dissociation (not measure of concentration)
• strong acids & bases: reaction with water is virtually 100% (strong electrolytes)

Question 7

What are some strong acids and bases? *

Answer 7

Strong acids:
HCl, HBr, HI
HNO3:nitric acid
H2SO4: sulfuric acid
HClO3: chloric acid
HClO4: perchloric acid
Strong bases:
NaOH, KOH, Ba(OH)2
All metal hydroxides

Question 8

What are some weak acids & bases?

Answer 8

-only small % dissociates (weak electrolytes)
Ex: acids: acetic acid & carbonic acid
Ex: bases: ammonia, pyridine, Aniline

Question 9

What does self-ionization mean?

Answer 9

• dissociation of water

Question 10

What is the ion product constant for water?

Answer 10

K(w)= [H3O+][OH-]

= 1.0 x 10^-14 (@ 25°C)

Question 11

What is the pH scale?

Answer 11

Scale that indicates acidity or basicity of a solution

• 0 (very acidic) to 14 (very basic)
• pH= -log[H3O+]

Question 12

How can pH impact H3O+ and OH- concentrations?

Answer 12

• if add an acid, [H3O+] increases & [OH-] decreases
• if add a base, [OH-] increases & [H3O +] decreases
• if equal amounts of base and acid then equal amounts of [H3O+] & [OH-]

Question 13

What does [H3O+] & [OH-] equal to?

Answer 13

1.0x10^-14 = [H3O+] [OH-]

Question 14

How can you calculate pH?

Answer 14

1.0x10^-14 = [H3O+] [OH-]
pH= -log [H3O+]

Question 15

How can you find [H3O+] from pH?

Answer 15

[H3O+]= 10^-pH

Question 16

What is a neutralization reaction?

Answer 16

Reaction of an act with a base to produce salt and water

Question 17

What is titration?

Answer 17

Analytical technique to determine concentration os an acid or base
- measures amount of standard solution to neutralize second, unknown solution

Question 18

What is a burst? Indicator?

Answer 18

Burnt: long glass tube calibrated in mL which contains standard solution
Indicator: substance which changes as pH changes

Question 19

What is a polyprotic substance?

Answer 19

Donates or accepts more than one proton per formula unit

ex: H2SO4 produces 2H+ ions

Question 20

What is a buffer solution?

Answer 20

Solution which resists large change in pH when either acids or bases are added
-buffer is lechatelier’s principle

Question 21

What is the buffer process?

Answer 21

• act to establish an equilibrium btwn conjugate acid/base pair
• consist of either: weak acid & its salt (conjugate base) or weak base & its salt (conjugate acid)

Question 22

What does the addition of a base(OH-) do to a buffer solution?

Answer 22

• OH- will react with H3O+ producing H2O
• acid in butter system dissociates to replace H3O+ consumed by + base
• net result is to maintain pH close to initial level
• loss of H3O+ (stress) compensated by dissociation of acid to produce more H3O+

Question 23

What does the addition of an acid ( H3O+) do to a buffer solution?

Answer 23

• H3O+ from acid will increase overall
• conjugate base in buffer system reacts with H3O+ to form more acid
• net result is to maintain H3O+ concentration & pH close to initial level
• compensated by reaction of conjugate by gain of H3O+ (stress) to produce more acid

Question 24

What is buffer capacity?

Answer 24

Measure of ability of a solution to resist large changes in pH when strong acid/strong base is added

Question 25

How do you calculate pH of a buffer solution?

Answer 25

[H3O+]=(Ka[acid]) / [conjugate base]

pKa= -log(Ka)

Question 26

What is the henderson-hasselbalch equation?

Answer 26

pH= pKa + log (B/A)

Used to find pH of a buffer solution

Question 27

What are the parts of an oxidation -reduction process?

Answer 27

• Oxidation: defined by one of following:
  
  • loss of e-, loss of hydrogen atoms, gain of oxygen atoms
• Reduction: defined by one of following:
  
  • gain of e-, gain of hydrogen, loss of oxygen
• cannot have oxidation without reduction*

Question 28

What does an an oxidizing agent do? Reducing agent?

Answer 28

Oxidizing Agent:
- is reduced, gains electrons, causes oxidization
Reducing Agent:
- is oxidized, loses electrons, causes reduction

Question 29

What is a voltaic cell?

Answer 29

Electrochemical cell that converts stored energy into electrical energy

• separates 2 half reactions
• makes electrons how through a wire to allow oxidation and reduce to occur
• salt bridge completes circuit

Question 30

Where does oxidation and reduction occur?

Answer 30

• Oxidation - anode

- reduction-cathode

Question 31

What is electrolysis?

Answer 31

Uses electrical energy to cause nonspontaneous oxidation-reduction reactions to occur (reverse of a voltaic cell)