Class Five

Question 1

Bronsted Lowry acids and bases

Answer 1

acids are proton donors

bases are proton acceptors

Question 2

Lewis acids and bases

Answer 2

acids are electron pair acceptors

bases are electron pair donors

Question 3

what is a conjugate base

Answer 3

when a BL acid donates a H+, the remaining structure is the conjugate base

Question 4

what is a conjugate acid

Answer 4

when a BL base accepts a H+, the remaining structure is the conjugate acid of the base

Question 5

difference between a BL acid and its conjugate base

Answer 5

conjugate base is missing a H+

Question 6

difference between BL base and its conjugate acid

Answer 6

conjugate acid has an extra H+

Question 7

what is a strong acid

Answer 7

dissociates completely in water

e.g. HCl

Question 8

what is a weak acid

Answer 8

dissociation in water does not go to completion

e.g. HF

Question 9

if K_a > 1 then..

Answer 9

products are favoured and it is a strong acid

Question 10

if K_a < 1 then..

Answer 10

reactants are favoured and the acid is weak

Question 11

the larger the K_a value..

Answer 11

the stronger the acid

Question 12

the smaller the K_a value..

Answer 12

the weaker the acid

Question 13

the 6 strong acids

Answer 13

HI

HBr

HCl

HClO₄

H₂SO₄

HNO₃

Question 14

the larger the K_b value..

Answer 14

the stronger the base

Question 15

the smaller the K_b value..

Answer 15

the weaker the base

Question 16

4 groups of strong bases

Answer 16

group 1 hydroxides (e.g. NaOH)

group 1 oxides (e.g. Li₂O)

some group 2 hydroxides (e.g. Ba(OH)₂)

metal amides (e.g. NaNH₂)

Question 17

the conjugate base of a strong acid..

Answer 17

has no basic properties in water

e.g. Cl- from HCl

Question 18

the conjugate base of a weak acid..

Answer 18

is a weak base

Question 19

the weaker the acid..

Answer 19

the stronger its conjugate base

Question 20

what does polyprotic

Answer 20

something that can donate more than one proton

Question 21

when is a substance amphoteric

Answer 21

when a substance can act as an acid or a base

Question 22

the conjugate base of a weak polyprotic acid..

Answer 22

is amphoteric always

Question 23

every time a polyprotic acid donates a proton..

Answer 23

the resulting species will be a weaker acid than the one before

Question 24

the lower the pKa..

Answer 24

the stronger the acid

Question 25

neutralization reaction

Answer 25

acid + base → salt + water

Question 26

neutralization formula

Answer 26

a x [A] x V_a = b x [B] x V_b

Question 27

where does buffer capacity come from

Answer 27

presence of a weak acid and its conjugate base (or vice versa)

Question 28

Henderson-Hasselbalch equation for acid

Answer 28

pH = pK_a + (conjugate base/weak acid)

Question 29

how to pick a buffer solution

Answer 29

choose a weak acid whose pK_a is close to the desired pH

Question 30

acid base titration

Answer 30

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

Question 31

explain the process of titration

Answer 31

adding a strong acid/base of known identity aka the titrant to a solution containing the unknown base/acid

Question 32

equivalence point

Answer 32

moles added = moles initially present

(moles of added OH- = moles of initial H+)

Question 33

half equivalence point

Answer 33

pKa = pH at half equivalence point

Question 34

what has more than one equivalence point

Answer 34

titration of a polyprotic acid

number of equivalence points = number of ionizable hydrogens

Question 35

what makes something more acidic (3)

Answer 35

more positive charge

more electronegativity

larger atom

Question 36

what makes something basic (3)

Answer 36

more negative

less electronegativity

smaller atom

Question 37

half equivalence point always is

Answer 37

the pKa of the weak acid or base