C4: Acids and Bases

Question 1

what is an arrhenius acid?
- arrhenius base?

Answer 1

• H+ donor
• OH- donor

Question 2

what is a bronsted lowry acid?
- bronsted lowry base?

Answer 2

• H+ donor
• H+ acceptor

Question 3

what is a lewis acid?
- lewis base?

Answer 3

• e- acceptor
• e- donor

Question 4

what does the Ksp expression for acids look like?
- if water is in the rxn, how is it expressed?

Answer 4

Ka = [H+][A-] /[HA]
- not in expression bc it is a solvent

Question 5

what is the formula for calculating pKa?

Answer 5

pKa = -logKa

Question 6

what are the 6 strong acids?

Answer 6

• hydroiodic acid (HI)
• hydrobromic acid (HBr)
• hydrochloric acid (HCl)
• perchloric acid (HClO4)
• sulfuric acid (H2SO4)
• nitric acid (HNO3)

Question 7

for strong acids in regard to Ka expressions:
- how do they dissociate?
- is a forward/ reverse rxn favored?
- large/small Ka?
- large/ small pKa?

Answer 7

• completely
• forward
• large
• small

Question 8

for weak acids in regard to Ka expressions:
- how do they dissociate?
- is a forward/ reverse rxn favored?
- large/small Ka?
- large/ small pKa?

Answer 8

• they dont, they like equilibrium
• reverse
• small
• large

Question 9

what does a large Ka value mean in regard to acid strength?
- small Ka?
- what about for Kb?

Answer 9

the larger the Ka the stronger the acid
- the smaller the Ka the weaker the acid
- same concept but for bases

Question 10

what is a polyprotic acid?

Answer 10

an acid that has more than one proton to donate, the first proton is always the strongest

Question 11

what does the Ksp expression for bases look like?

Answer 11

Kb = [HB+][OH-]/ [B]

Question 12

what is the formula for calculating pKb?

Answer 12

pKb = -logKb

Question 13

for strong bases in regard to Kb expressions:
- how do they dissociate?
- is a forward/ reverse rxn favored?
- large/small Ka?
- large/ small pKa?

• what are they answers to these questions for weak bases?

Answer 13

same as strong acids/ strong bases respectfully

Question 14

what are the 4 groups of common strong bases?

Answer 14

• group 1 hydroxides (ex: NaOH)
• group 1 oxides (ex: Li2O)
• some group 2 hydroxides (Ba(OH)2, Sr(OH)2, Ca(OH)2)
• metal amides (ex: NaNH2)

Question 15

an acid corresponds to its ____ and a base corresponds to its ____

Answer 15

conjugate base; conjugate acid

Question 16

the stronger the acid/base, the weaker its ____. BUT there is also an option to be so weak that the molecule is ____

Answer 16

conjugate acid/base; neutral

Question 17

what does the Ksp expression for water look like?
- this expression is also equal to ____

Answer 17

Kw = [H3O+][OH-]
- 1x10^-14

Question 18

for any conjugate pair, the Kw = ____

Answer 18

Kw = KaKb

Question 19

pKa + pKb = ____

Answer 19

14

Question 20

water is amphoteric, what does this mean?

Answer 20

it can act as an acid or base

Question 21

• if pH is greater than 7….
• if pH is equal to 7….
• if pH is less than 7….

Answer 21

• basic
• neutral
• acidic

Question 22

pH = ____

Answer 22

pH = -log[H+]

Question 23

pOH = ____

Answer 23

pOH = -log[OH-]

Question 24

pH + pOH = ____

Answer 24

pH + pOH = 14

Question 25

how would you calculate the pH of 1x10^-4? - what about for 5x10^-8?

Answer 25

- since it is 1x10, just take the - off the exponent. = 4 - first take care of the exponent the same way as before (=8), then since its now 5x10 just subtract 1 from the 8 (between 7-8)

Question 26

what is a neutralization rxn?

Answer 26

when an acid and a base are combined. often produces a salt and water

Question 27

a neutralized rxn is endo or exothermic? - complete neutralization requires ____ of H+ and ____

Answer 27

- exothermic - equal moles; OH-

Question 28

what is the formula for calculating a neutralized rxn?

Answer 28

na * Va * Ma = nb * Vb * Mb where, n= equivalents of H+ or OH- per acid or base M= molarity or concentration

Question 29

a salt is a ____ and an ____

Answer 29

cation; anion

Question 30

what are the pH's of a salt under the following conditions: - acidic - neutral - basic

Answer 30

- pH < 7 - pH = 7 - pH > 7

Question 31

the pH of a salt depends on....

Answer 31

where the ions came from, the strength of the original acids/bases need to be evaluated

Question 32

what is a buffer? - what is the ratio of weak acids/bases present when a buffer is involved - what happens if you add some acid or base? - will adding a small amount of water to a buffer change its buffering ability? - what does the relationship between pka and pH look like when a buffer is present?

Answer 32

a solution that resists changes in pH when an acid or base is added - equal amounts of weak acids/bases and their conjugate acid/base - pH changes a little bit - yes, its ability is lowered - pKa should be close to the pH you want to buffer

Question 33

what is a titrant?

Answer 33

a strong acid/base of known identity

Question 34

what is an acid- base titration?

Answer 34

an experimental technique used to determine the identity of an unknown weak acid or weak base by determining its pKa or pKb

Question 35

describe the aspects to a acid-base titration curve

Answer 35

CHECK FOLDER

Question 36

what does an acid-base titration curve of a strong acid with a strong base look like?

Answer 36

CHECK FOLDER

Question 37

what does the acid-base titration curve of a weak acid with a strong base look like?

Answer 37

CHECK FOLDER

Question 38

what does the acid-base titration curve of a polyprotic acid with hydroxide look like?

Answer 38

CHECK FOLDER