AP Acids and Bases Concepts

Question 1

What is the Arrenhius definition of an acid?

Answer 1

an Arrenhius acid has an H+

Question 2

What is the Arrenhius definition of a base?

Answer 2

an Arrenhius base has an OH-

Question 3

What is the Bronsted-Lowry (BL) definition of an acid?

Answer 3

a BL acid donates a proton (H+)

Question 4

What is the Bronsted-Lowry (BL) definition of a base?

Answer 4

a BL base accepts a proton (H+)

Question 5

What is an amphoteric compound? What is an example of an amphoteric compound?

Answer 5

a compound that can act as an acid or a base; water

Question 6

What will a BL acid always produce in water?

Answer 6

hydronium (H3O+)

Question 7

What will a BL base always produce in water?

Answer 7

hydroxide (OH-)

Question 8

What are Ka and Kb?

Answer 8

dissociation constants for acids (a) and bases (b)

Question 9

If K > 1, reaction shifts

Answer 9

right (more products than reactants)

Question 10

If K

Answer 10

left (more reactants than products)

Question 11

What is Kw?

Answer 11

the ion product constant for water

Question 12

What does Ka*Kb equal?

Answer 12

1 x 10^-14 (Kw)

Question 13

What is pKa?

Answer 13

the pH at the half equivalence point in a titration

Question 14

What do pKa and pKb equal?

Answer 14

pKa = -logKa
pKb = -logKb

Question 15

What does pKa + pKb equal?

Answer 15

14

Question 16

What is pH?

Answer 16

a measure of the acidity of alkalinity of a solution

Question 17

What does strong mean (in terms of acids and bases)?

Answer 17

completely breaks up in water (completely dissociates

Question 18

True/False: strong acids and bases have very large Ka or Kb values

Answer 18

True

Question 19

What are common strong acids?

Answer 19

HCl, HBr, HI, H2SO4, HNO3, HClO4

Question 20

The stronger the acid, the ___ the conjugate base

Answer 20

weaker

Question 21

The stronger the base, the ___ the conjugate acid

Answer 21

weaker

Question 22

What are common strong bases?

Answer 22

LiOH, NaOH, KOH, Ca(OH)2, Mg(OH)2, Sr(OH)2, Ba(OH)2 (last 4 are sparingly soluble)

Question 23

What does a metal oxide and water make?

Answer 23

a metal hydroxide

Question 24

If temperature increase, K

Answer 24

decreases

Question 25

If temperature decrease, K

Answer 25

increases

Question 26

What is the pH of a strong acid/base?

Answer 26

the -log of the given concentration of the acid (becuase it dissociates completely)

Question 27

How to find the pH of a weak acid or base

Answer 27

1) write out fast and reversible equation
2) write ICE table
3) in initial concentration for weak acid/base write given concentration
4) write in 0’s for everything else in initial concetration
5) set up equilibrium expression and solve for x (avoiding quadratic when you can)

Question 28

How to find Ka/Kb when given a concentration and the pH

Answer 28

1) write out fast and reversible equation
2) write ICE table
3) find concentration of [H3O+] by using pH = -log[H3O+]
4) plug that value in for every x you see in the ICE table
5) write equilibrium expression and solve for Ka/Kb

Question 29

What is a polyprotic acid?

Answer 29

an acid that has more than one proton (H+)

Question 30

The first proton in a polyprotic acid has a ___ Ka than the second

Answer 30

higher

Question 31

When equilibrating polyprotic acids only the ___ reaction needs to be used

Answer 31

first

Question 32

What does a buffer contain?

Answer 32

an acid and its conjugate base

Question 33

What does a buffer do?

Answer 33

resists a change in pH when an acid or base is added to the buffered solution

Question 34

The more concentrated the buffer, the ___ it resists a change in pH

Answer 34

better

Question 35

How to find the pH of a buffered solution

Answer 35

1) write out fast and reversible equation
2) write ICE table
3) in initial write given initial concentrations of acid and buffer
4) finish ICE table
5) write equilibrium expression
6) solve for x
7) plug this number into pH = -log[H3O+]

Question 36

How to find the pH of a buffered solution with an addition of a strong acid

Answer 36

1) write out fast and reversible equation
2) write ICE table
3) find concentration of H+ of the strong acid and subtract it from the concentration of the buffer (find the moles of the strong acid, make mole ratio to find moles of H+, divide moles of H+ by total volume –> volume of bufferd solution and strong acid)
4) solve as you normally would for a buffer

Question 37

To find a good buffer pair, you want the pH of the buffer as close to the

Answer 37

pKa as possible

Question 38

What is an ideal mole ratio for a buffer?

Answer 38

1:1

Question 39

What are the three types of titrations you can have?

Answer 39

1) strong acid & strong base (equivalence point at 7)
2) strong acid & weak base (equivalence point below 7)
3) weak acid & strong base (equivalence point above 7)

Question 40

What is titration?

Answer 40

the addition of a strong or weak acid or base with a strong or weak acid or base until it reaches equivalence

Question 41

What is the equivalence point?

Answer 41

when the number of moles of acid equals the number of moles of base

Question 42

What is the endpoint?

Answer 42

when the indicator changes color

Question 43

When does a color change happen?

Answer 43

when the pH changes

Question 44

How to do math for a titration

Answer 44

1) write equation for acid and base
2) write moles, volume, and concentration of each given
3) use stoichiometry to find moles of unknown

Question 45

What to do if you are asked for pH of solution at equivalence point

Answer 45

(assuming that the titration goes to completion –> no more reactants and any conjugate on the product side reacts with water)

1) add up total volume
2) use mole ratio to find out moles and concentration of product
3) ICE
4) if need be find Kb to solve for x