Acid, Base and pH 1

Question 1

What is an Arrhenius base?

Answer 1

• acid - produces (H+) hydrogen ion and anion in water
• base - produces (HO-) hydroxide or hydroxyl ion and a cation in water

Question 2

What is a Brønsted–Lowry Acid?

Answer 2

A proton (H+) donor

Question 3

What is a Brønsted–Lowry base?

Answer 3

A proton (H+) acceptor

Question 4

What is a Lewis acid?

Answer 4

species that accept electrons and it is termed as an electrophile, and are electron deficient species

Question 5

What is a Lewis base?

Answer 5

species that donate electrons to a nucleus with an empty orbital and is a nucleophile

Question 6

What are 2 Acid/Base reactions that occur in our body?

Answer 6

CO2 + H2O —> H2CO3
- CO2 transported in the blood reacts with water to form carbonic acid which is excreted by the lungs as a gas
Ca(OH)2 + 2HCl —> CaCl2 + 2H2O
- Antacid - Ca(OH)2 - neutralises
- Stomach acid - 2HCl

Question 7

What are most drugs?

Answer 7

• Weak Acids
• Bases

Question 8

What does an Acid produce in water?

Answer 8

• hydrogen ion (H+)
• an anion

Question 9

What does a base produce in water?

Answer 9

• hydroxide or hydroxyl ion (HO-)
• a cation

Question 10

What does a neutralisation reaction produce?

Answer 10

A salt

Question 11

What is a salt?

Answer 11

Ionic compound made from an anion and cation

Question 12

What is the limitation of strong acids and strong bases?

Answer 12

limited to Aqueous solutions

Question 13

What occurs in an acid-base reaction?

Answer 13

a proton (H+) is transferred from an acid to a base

Question 14

What are weak bases?

Answer 14

the conjugated base of strong acids - tends to accept protons

Question 15

What is the Equilibrium constant?

Answer 15

k = Conc of products / conc of reactants

Question 16

What is Ka?

Answer 16

Acidity Constant

Question 17

What do strong acids produce in terms of Ka?

Answer 17

• large Ka
• High H3O+ concentration
• completely dissociated

Question 18

What do strong bases produce in terms of Ka?

Answer 18

• small values for Ka
• low H3O+ concentration
• less dissociated

Question 19

What is the range of pKa values?

Answer 19

2-12

Question 20

What value of pKa shows a strong acid?

Answer 20

Less than 3

Question 21

What value of pKa shows a weak acid

Answer 21

Greater than 3

Question 22

What 5 factors influence acidity?

Answer 22

• increasing electronegativity
• increasing bond energy
• inductive effects
• Hybridisation effect
• resonance/delocalisation effects

Question 23

How do electron donating and withdrawing groups influence acidity?

Answer 23

by destabilising or stabilising the conjugate base
- Withdrawing increases acidity
- donating decreases acidity

Question 24

What is pKb?

Answer 24

Conjugated base of the acid

Question 25

What is the pKw Equation?

Answer 25

pKw = pKa + pKb

Question 26

What value is the pKw constant?

Answer 26

14

Question 27

What is basicity?

Answer 27

The ability of a compound to use its nonbonding electrons to combine with a proton

Question 28

What influences basicity? 4 Examples

Answer 28

• electronegativity
• inductive effects
• hybridisation effect
• resonance/delocalisation effects

Question 29

What influence does electronegativity have on basicity?

Answer 29

Increasing electronegativity decreases basicity