Acids And PH

Question 1

Acid

Answer 1

Proton donor

Question 2

Base

Answer 2

Proton acceptor

Question 3

Alkali

Answer 3

Base that’s soluble in water

Question 4

Acid base general equation

Answer 4

HA + B —> BH+ + A-
A + B —> CA + CB

Question 5

Conjugate base

Answer 5

Base derived from acid

Question 6

Conjugate acid

Answer 6

Acid derived from a base

Question 7

Strong acid definition and example

Answer 7

Ions fully dissociated in water
HCl —> Cl- + H+

Question 8

Weak acid definition and example

Answer 8

Ions slightly dissociated in water
CH3CO2H —>< H+ + CH3CO2
constant k indicates dissociation level

Question 9

Mono/di/tri basic acid examples and dissociation trend

Answer 9

Mono hydrochloric HCl
Di sulphuric H2SO4
Tri phosphoric H3PO4
1st dissociation strongest
3rd dissociation weakest

Question 10

pH definitions and equation

Answer 10

H+ conc
pH = -log[H+]
[H+] = 10^-pH

Question 11

Strong Vs weak acid trends in pH and [H+]

Answer 11

Strong, +pH 1, xconc 10
Weak, +pH 1, xconc 20

Question 12

Mono/di/tri strength compared to [acid]

Answer 12

Mono =
Di >/=
Tri >

Question 13

Kw equation and alkaline solutions

Answer 13

Kw = [H+] x [OH-] = 1x10^-14
298K, pure water
[H+] = Kw/[OH-]

Question 14

Strong acid and alkali calculations

Answer 14

Mol H+/OH- before mixing
Find excess conc
Moles/new total vol
Kw, find new H+
Use pH equ

Question 15

Amphoteric

Answer 15

Accept/donate protons simultaneously

Question 16

Ka expression and simplification

Answer 16

([H+][A-])/[HA]
[H+]^2/[acid]

Question 17

Ka assumptions and their effect

Answer 17

Acid provides more H= than water, ignore water H+, [H+] = [A-], overestimate top
Fails when [H+] is very small/close to Kw
Little dissociation, most acid is HA, [acid] = [HA], overestimate bottom
Fails when [H+] is very large/close to 1

Question 18

Titration curve marking points

Answer 18

Ph vs acid/alkali volume
Start pH
Flattish start
Vertical/equivalence volume
Vertical length
Final pH (never reaches 14, initial acid dilutes)

Question 19

Describe the different titration curves

Answer 19

SS steep, steep
SW steep, gentle
WS gentle, steep, initial rapid
WW gentle, gentle, initial rapid
Di/tri protein, multiple equivalence/midpoints

Question 20

Calculating Ka from a titration curve

Answer 20

Half equ point
A- = HA
A-/HA = 1
Ka = [H+]
(-log = p)
PKa = pH

Question 21

Indicator compositions and equation

Answer 21

Weak acid and cb that are different colours
Changes colour at equivalence point
PKin = mid pH range
Hin —>< in- + H+
PKin = constant
Kin = ([in-][H+])/[Hin]

Question 22

Methyl orange range and exclusion

Answer 22

3.7
Weak acid

Question 23

Phenolphthalein range and exclusion

Answer 23

9.3
Weak base

Question 24

Buffer composition ad function

Answer 24

Resist pH change in industrial/biochemical systems
Still changes pH a bit
Weak acid + cb

Question 25

Buffer equation

Answer 25

[A-] /= [H+]
(More A- added)
[HA] = [acid]
(Little HA dissociation)
[A-] = [base]
(A- from cb > A- from HA)
Ph = pKa + log [base]/[acid]

Question 26

Buffer equation considerations

Answer 26

Ratio matters not actual values
Concs after mixing
Concs before mixing get diluted
B > a, +, pH > pKa
A > b, -, pKa > pH

Question 27

Buffer relative amounts

Answer 27

HA —>< H+ + A-
Lots, Little, lots

Question 28

Add acid to buffer

Answer 28

Added H+ and buffer A- —> HA
More HA
Less A-
Small ratio change, large initial values
Decrease ration, increase [H+] slightly

Question 29

Add alkali to buffer

Answer 29

Added A- and buffer HA —> H2O + A-
More A-
Less HA
Small ratio change, large initial values
Increase ration, decrease [H+] slightly