Ch 7.1 _ A-B equilibrium

Question 1

What is the name of the compound able to behave either as an acid or a base?

Answer 1

Ampholyte, able to release or gain protons

Question 2

What is an acido-base reaction?

Answer 2

2 acido-base couples exchanging the same number of protons

Question 3

Def autoprotolysis of water

Answer 3

Water reacting with itself

Question 4

What is Kw?

Answer 4

Autoprotolysis constant for water Kw; Equilibrium constant; Self-ionization constant
Kw = aH3O+ x aOH- = [H3O+] x [OH-]
Kw = 10^-14 => pKw = -log Kw = 14 (T = 298K)

Question 5

What is Ka?

Answer 5

Acid disassociation constant; Acidity constant Ka
Ka = [H3O+] x [A-] / [AH]
pKa = - log Ka

Question 6

What is the basicity constant?

Answer 6

Basicity constant Kb
Kb = [OH-] x [BH+] / [B]
pKb = - log Kb
Ka x Kb = Kw

Question 7

What means an increase in acidity?

Answer 7

Acidity increases => Acid stronger as it can easily release a proton => Reaction shifted in the forward direction => Ka higher, pKa smaller

Question 8

What is pKa & what it tells us?

Answer 8

Acidity scale pKa
pKa < 0 AH strong & A- spectator
0 < pKa < 14 AH & A- weak
14 < pKa AH spectator & A- strong

Question 9

When a reaction is total?

Answer 9

K > 10^4 or delta pKa > 4