Properties of Solutions (Acids + Bases + Buffers + titrations)

Question 1

what is the ionic product of water

Answer 1

1 x 10^-14

Question 2

what is a bronsted-Lowry acid ?

Answer 2

proton (H+) donor

Question 3

what is a Bronsted-Lowry Base?

Answer 3

proton (H+) acceptor

Question 4

what does amphoteric mean ?

Answer 4

able to act as both an acid and a base.

Question 5

what is an Arrhenius acid?

Answer 5

a species which increases the number of H30+ ions when dissolved in water (pH decreases)

Question 6

what is a Arrhenius base?

Answer 6

a species which increases the number of OH- ions when dissolved in water (pH increases)

Question 7

what is a lewis acid

Answer 7

electron pair acceptor

Question 8

what is a lewis base

Answer 8

electron pair donor

Question 9

the Arrhenius acids are limited to …

Answer 9

aqueous solutions

Question 10

the equation for strong acid pH =

Answer 10

-log (c H30+/c standard)

Question 11

in an acid base reaction the equilibrium favours the side with the … this is because…

Answer 11

weaker acid and base, because they are more stable and have lower potential energies.

Question 12

how do we determine the pH of weak acids/bases

Answer 12

first we find the equilibrium constant - in this case known as the Ka (acid dissociation constant)

Question 13

Ka of pure liquids =

Answer 13

1

Question 14

using the Ka we can calculate the …

Answer 14

pKa

Question 15

for weak acids the equilibrium lies far to the…

Answer 15

left

Question 16

after finding x in the pH weak acid calculations, how do you find the pH?

Answer 16

pH = -logx

Question 17

pKa + pKb =

Answer 17

pKw = 14

Question 18

Ka x Kb =

Answer 18

Kw

Question 19

what is the inductive effect?

Answer 19

occurs when electron-withdrawing or electron-donating groups in a molecule cause a change in electron density. this causes the pH to change.

Question 20

inductive effect -

the more electronegative the bonding group the ____ the acid

Answer 20

stronger

Question 21

inductive effect -

the _____ the bonding group the stronger the acid

Answer 21

closer

Question 22

inductive effect -

the ____ of the bonding group the stronger the acid

Answer 22

more

Question 23

the ___ resonance forms the ____ stable the anion and hence the stronger the acid

Answer 23

more, more

Question 24

what makes up a buffer solution?

Answer 24

mix of either a weak acid or base and its corresponding salt.

Question 25

what is the first step of finding buffer pH of the weak acid and strong base titration?

Answer 25

calculating the initial moles of the reactants

Question 26

what is the second step finding buffer pH of the weak acid and strong base titration?

Answer 26

calculating the final moles of the weak acid and its conjugate base

Question 27

final moles of the weak acid =

Answer 27

initial moles of weak acid - initial moles of strong base

Question 28

final moles of conjugate base =

Answer 28

initial moles of strong base

Question 29

what is the 3rd step of find the buffer pH of a weak acid and strong base titration?

Answer 29

using the buffer pH equation

Question 30

how do you find the pKa from the Ka

Answer 30

pKa = -log(Ka)

Question 31

what is the equivalence point?

Answer 31

when the same volume of the acid and base have been used in the titration

Question 32

what is the halfway point

Answer 32

when half the volume of weak acid (in the burette) is added to the base.

Question 33

what does association mean ?

Answer 33

the addition of two or more substances together to form a larger entity

Question 34

what is the Kw of water ?

Answer 34

1 x 10 -14

Question 35

the pKa of strong acids is a ___ number

Answer 35

small

Question 36

the Ka of a strong acid is a _____ number

Answer 36

big

Question 37

is ammonium an acid or a base

Answer 37

NH4+ is an weak acid

Question 38

is ammonia an acid or a base

Answer 38

NH3 is a weak base

Question 39

how do you calculate the initial pH of a buffer solution - titration q

Answer 39

same why as normal weak acid/base pH calculations - without - x on the bottom.

Question 40

how do you calculate the pH of a buffer solution during the reaction - titration q (random and halfway point)

Answer 40

finding initials and finals.

Question 41

how do you find the concentration of the conjugate base in an equivalence point q (when the volumes are equal.

Answer 41

since the nACID = nBASE = nCONJBASE. this means that cCONJBASE = n/Vtotal

Question 42

what should we do In the equivalence point equilibrium qs

Answer 42

1. find the final concentration of the conj base. 2. set up dissociation equilibrium reaction. 3. same as weak base pH questions - you don't need to put - x on the bottom.

Question 43

what are the 3 assumption points for weak acids in a equilibrium reaction when finding the pH

Answer 43

1. acid is a weak acid . 2. eq. lies far to the left. 3. assume dilute solutions.

Question 44

what are the assumptions for buffer questions ?

Answer 44

1. acid is a weak acid and doesn't fully dissociate, assume the concentration = c. 2. conj base (from main equilibrium reaction) is a weak conj base and dissociates into conj base from specific reaction and the metal ion. assume conj base from specific reaction = c of conj base from main equilibrium.

Question 45

how does the inductive effect work.

Answer 45

a high electronegative group near the site of interest pulls the electron density towards itself (I-), this causes the site of interest to become more stable and therefore strengthen the acid.