12.1

Question 1

an acid is a proton…

Answer 1

donor

Question 2

a base is a proton…

Answer 2

acceptor

Question 3

when does a molecule which contains hydrogen act as an acid

Answer 3

if the hydrogen carries a slightly positive charge

Question 4

what makes a molecule a base

Answer 4

it must contain a lone pair in order to form a dative covalent bond

Question 5

what is a conjugated acid-base pair

Answer 5

consists of either a base and its conjugate acid or an acid and its conjugated base

Question 6

state the conjugated pairs for this reaction
HCl + H2O <=> H3O+ + Cl-

Answer 6

Cl- & HCl
H2O & H3O+

Question 7

what is meant by monoprotic

Answer 7

a species that can donate 1 proton

Question 8

what is meant by diprotic

Answer 8

a species that can donate 2 protons

Question 9

what is an amphoteric substance

Answer 9

one that can act both as an acid and as a base

Question 10

how do you define a strong acid

Answer 10

one that almost completely dissociates in aqueous solutions

Question 11

how do you define a weak acid

Answer 11

one that only partially dissociates in aqueous solutions

Question 12

what is the equation for pH

Answer 12

pH = -log[H+]

Question 13

what does Ka stand for

Answer 13

acid dissociation constant

Question 14

what is the general equation for Ka

Answer 14

Ka = [H+(aq)] [A-(aq)] / [HA(aq)]

Question 15

what is the equation for Ka in strong acids

Answer 15

Ka = [H+(aq)] / [HA(aq)]

Question 16

what is the equation for pKa

Answer 16

pKa = -logKa

Question 17

How does pKa and Ka effect the pH of an acid

Answer 17

as Ka increases pH decreases
as pKa decreases pH decreases

Question 18

what is the equation for self-ionization of water

Answer 18

Kw = [H+(aq)] [OH-(aq) / [H2O(l)]

Question 19

How is the equation for ionisation of water simplified at a stated temperature

Answer 19

Kw = [H+(aq)] [OH-(aq)]

Question 20

what does Kw stand for

Answer 20

the ionic product of water

Question 21

how do you define a neutral solution

Answer 21

one in which the hydrogen ion concentration is equal to the hydroxide ion concentration

Question 22

what is the equation for pKw

Answer 22

pKw = -log Kw

Question 23

why do even the most alkaline solutions still contain some hydrogen ions

Answer 23

because of the fact that water self-ionises

Question 24

how can the relative strengths of different acids or bases be determined

Answer 24

by measuring the pH of equimolar aqueous solutions of the acids/bases, at the same temperature

Question 25

what is the pH of a salt formed from a strong acid and a strong base

Answer 25

7

Question 26

what is the pH of a salt formed from a weak acid and a strong base

Answer 26

>7

Question 27

what is the pH of a salt formed from a strong acid and a weak base

Answer 27

<7

Question 28

what is the pH of a salt formed from a weak acid and a weak base

Answer 28

dependent on the relative strengths of the acid and base

Question 29

how is pH effected when a strong acid is diluted by a factor of 10

Answer 29

pH increases by a factor of 1 for each 10-fold decrease in concentration

Question 30

how is pH effected when a weak acid is diluted by a factor of 10

Answer 30

pH value increases by a factor of about 0.5 for each 10-fold decrease in concentration

Question 31

how can Ka of a weak monobasic acid such as benzoic acid by determined experimentally

Answer 31

accurately weigh between 0.4-0.5g of the acid dissolve it in roughly 50cm^3 of deionised water transfer solution to a 250cm^3 volumetric flask and add washings from the beaker using deionised water to make the solution up to the mark mix by inverting the flask then withdraw a sample and use a calibrated pH meter to measure the pH of the solution then caluclate the Ka value

Question 32

what are the issues with calculating Ka experimentally

Answer 32

you must assume that the concentration of the acid at equilibrium is identical to the original concentration of the acid however it is not as it may have dissociated slightly the accuracy of the measurement of pH as this largely effects the Ka calculated due to small amounts being used