Lecture 6

Question 1

What is an Acid?

Answer 1

Form H+ (only positively charged ions) when dissolved in WATER.

Question 2

What is a Base?

Answer 2

Form OH- when dissolved in WATER.

Question 3

Give the three definitions of an alkali:

Answer 3

• Form OH- (only negatively charged ions) when dissolved in water, eg. NaOH.
• A BASIC salt of an alkali metal or alkaline earth metal.
• WATER SOLUBLE bases.

Question 4

What is the Arrhenius definition of an acid?

Answer 4

Produces H+ when dissolved in water.

Question 5

What is the Arrhenius definition of a base?

Answer 5

Produces OH- and a cation in aqueous solution.

Question 6

What is Arrhenius concept of neutrality?

Answer 6

[H+]=[ OH-]

Question 7

What is Bronsted- Lowry definition of an acid?

Answer 7

H+ DONOR

Question 8

What is Bronsted- Lowry definition of a base?

Answer 8

H+ ACCEPTOR

Question 9

What is Bronsted- Lowry concept of neutrality?

Answer 9

NO concept of neutrality.

Question 10

What is the Lewis definition of an acid?

Answer 10

An electron- pair acceptor.

Question 11

What is the Lewis definition of a base?

Answer 11

An electron pair donor.

Question 12

What is the general neutralisation reaction?

Answer 12

Acid + Base → Salt + Water

Question 13

What is a cation?

Answer 13

Positive Ion

Question 14

What is an anion?

Answer 14

Negative Ion

Question 15

In a neutralisation reaction what is the salt?

Answer 15

The compound formed by the CATION of the BASE and the ANION of the ACID.

Question 16

What are conjugate base pairs?

Answer 16

When an acid/base ONLY differs by the PRESENCE of a H+.

Question 17

What is defined as a strong acid?

Answer 17

An acid which FULLY dissociates.

Question 18

What is defined as a weak acid?

Answer 18

An acid which only PARTIALLY dissociates.

Question 19

What is Ka?

Answer 19

Quantified value for the equilibrium and is also known as the ACID DISSOCIATION CONSTANT.

Question 20

What is pH?

Answer 20

CONCENTRATION of H+.

Question 21

What is pOH?

Answer 21

BASICITY

Question 22

How do you work out pH?

Answer 22

pH= -log10[H+]

Question 23

How do you work out pOH?

Answer 23

pH= -log10[OH-]

Question 24

For the increasing acid strength, what happens to Ka, [H3O+] and pH?

Answer 24

Increase- Ka and [H3O+]

Decrease- pH

Question 25

For the increasing base strength, what happens to Kb, [H3O+] and pH?

Answer 25

Increase- Kb and pH | Decrease- [H3O+]

Question 26

What is Kw?

Answer 26

The ion product of water. | Kw= [H+][OH-] = 1x10(-14) at 25oC.

Question 27

What is an indicator?

Answer 27

WEAK ACID molecules that change colour with a change of the EQUILIBRIUM position.

Question 28

What is the range of the indicator- phenolphthalein?

Answer 28

0- 8.2- Colourless & 8.2-12- Pink

Question 29

What is the range of the indicator- anthocyanin?

Answer 29

Acid- Red Base- Blue

Question 30

What is the Henderson- Hasselbalch Equation?

Answer 30

pH= pKa + log ([A-]/ [HA])

Question 31

Ka Equation:

Answer 31

Ka= [H+][A-]/ [HA]

Question 32

What is a buffer solution?

Answer 32

A BUFFER solution RESISTS changes in pH upon the addition of SMALL amounts of either acid or base.

Question 33

What is a buffer made up of?

Answer 33

WEAK ACID and its SALT | WEAK BASE and its SALT.

Question 34

How does bicarbonate in plasma maintain blood pH?

Answer 34

BUILD up of ACIDIC METABOLITES (eg. lactic acid). Kidneys failure of acid/ base reactions by providing bicarbonate and excreting hydrogen ions leads to RESPIRATORY acidosis/ alkalosis with too much/ little CO2 exchanged in the lungs.

Question 35

How does haemoglobin in erythrocytes main blood pH?

Answer 35

Hydrogen ions are produced by DISSOCIATION of H2CO3. PROTONATION reduces AFFINITY of haemoglobin for O2 so O2 released in peripheral tissues. Haemoglobin can also transport CO2- also favours oxygen release.