Acidic and Basic Salts

Question 1

What is LCP?

Answer 1

LCP states if a system is not at equilibrium, the reaction will favour the formation of the products or reactants to establish equilibrium

Question 2

What is the formula for carbonic acid?

Answer 2

H2CO3

Question 3

What is the formula for critic acid?

Answer 3

C6H8O7

Question 4

What is the pH range for methyl orange?

Answer 4

3.1-4.4

Question 5

What is the pH range for Bromothymol Blue?

Answer 5

6.0-7.6

Question 6

What is the pH range for litmus?

Answer 6

5.5-8.0

Question 7

What is the pH range for phenolphthalein?

Answer 7

8.3-10.0

Question 8

Describe the process of shifting in equilibriums of acids and bases.

Answer 8

According to LCP, as [H3O+] changes, an equilibrium will shift to elicit a colour change, hence behaving as an indicator.

Question 9

What happens when an acid is added to the system?

Answer 9

The increase of [H3O+] prompts the equilibrium to shift left producing ___. Therefore, as the environment becomes more acidic, the colour shows ___.

Question 10

What was Lavoisier’s definition? State the flaws of his theory.

Answer 10

He stated that acids contained oxygen.
1. Acidic sub. lacked Oxygen, like HCl and HF
2. Oxygen containing sub. were basic

Question 11

What does Davy’s definition state? What were the limitations?

Answer 11

Davy’s definition is that acids were substances which contained replaceable hydrogens. Some acidic substances did not contain hydrogen like oxides
- the theory also did not take in account for the basic nature of basic oxides

Question 12

What was Svante Arrhenius’s theory?

Answer 12

Acids were substances, which, in aqueous solutions, ionized to form H+ ions. And bases as substances, in aqueous solutions, that dissociated into OH- ions.

Question 13

What does Bronsted-Lowry’s definition state?

Answer 13

An Acid was defined as a substance which tends to donate protons (H+). In aq. solns, the acid donates a proton to a water molecule, forming the hydronium ion (H3O+)

Question 14

Is an acid base reaction an exothermic reaction?

Answer 14

yes, an exothermic proton transfer reaction

Question 15

What are the advantages of BL theory/.

Answer 15

• Explains the behaviour of acids/bases and reactions in non-aqueous solns.
• Considers the role of solvent in the strength of an acid
• Explains how some ions will act as an acid or base
  -Explains the existence of non-hydroxide base
  Explains how some species can act as an acid and base - amphiprotic

Question 16

What is an amphiprotic substance?

Answer 16

A substance that can donate a proton or accept a proton depending on its chemical environment

Question 17

Give three examples of monoprotic acids.

Answer 17

acetic, hydrochloric acid, hydrofluoric, nitric

Question 18

Give two examples of diprotic acids

Answer 18

carbonic acid and sulfuric acid

Question 19

Give two examples of triprotic acids.

Answer 19

Phosphoric and critic acids

Question 20

What is a strong acid?

Answer 20

A strong acid is one that completely ionises in solution to form hydronium ions.

Question 21

What is a weak acid?

Answer 21

One which does not completely ionise in aqueous solutions to form hydronium ions

Question 22

Tricker - H2SO4 has its first ionisation as strong, but its second one as weak

Question 23

How do we calculate the pH of a concentration?

Answer 23

pH = -log10 [H3O+]

Question 24

SA + SB =

Answer 24

neutral salt

Question 25

SA + WB =

Answer 25

Acidic salt

Question 26

WA + SB =

Answer 26

Basic salt

Question 27

What is titration?

Answer 27

Titration is a technique by which the concentration of a solution is determined by measuring the volumes of solutions involved in the reaction.

Question 28

What are the four steps in titration?

Answer 28

1. Selection of a primary standard
2. Preparation of the Standard solution
3. Selection of an appropriate indicator
4. Rinsing of Glassware

Question 29

Provide an example of an application of a neutralization reaction.

Answer 29

Many ppl suffer from acid reflux, in which acid (HCl) from the stomach regurgitates into the lower oesophagus and causes a burning pain.
To reduce the severity, GPs will prescribe antacid tablets, which neutralise the acid in the stomach, increasing the pH and reducing irritation

Question 30

Describe the trend of a strong acid and strong base on a ph and cond. graph.

Answer 30

strong to strong, and eq at 7
conductivity - absolute value graph

Question 31

SA + WB

Answer 31

Lower than 7 pH
- decreasing obtuse angle graph for conductivity

Question 32

WA + SB

Answer 32

Upwards obtuse angle

Question 33

WA + WB

Answer 33

flatter, less steep hill
conductivity - rollercoaster

Question 34

Describe the graph of strong acid and strong base.

Answer 34

Titration cure - pH is low due to the high [H+], then increases as base is added -> eq. pt at pH = 7 due to a neutral salt being produced -> pH increases as more base is added

Cond. graph: High conductivity due to the high [H+] lowers as ions are neutralised by addition of a base - conductivity increases as more basic ions are increased

Question 35

Describe the graph of a Strong acid and weak base

Answer 35

pH is low due to the high [H+] from strong acid, then increases as base is added - eq pt is less then 7, as an acidic salt is produced - pH increases

Question 36

What is a buffer?

Answer 36

A buffer is composed of similiar/comparable conc. of a weak acid/base and its ocnjugate, which resists the change in pH if another acid or base is added.

Question 37

Describe how H2CO3/HCO3 is a buffer.

Answer 37

1. Definition
2. Weak acid is H2CO3 and its conjugate HCO3
3. LCP states that if a system at dyn. eq. is disturbed, the system wil shift.