ACIDS & BASES

Question 1

Autoprotolysis

Answer 1

The self-ionisation of two identical molecules (usually water) in which one acts as a Bronsted acid by donating a proton and the other as a Bronsted base by accepting the proton.

Question 2

Kw

Answer 2

1 x 10^-14

Question 3

All acid-base equations

Answer 3

• pKa+pKb = 14
• pOH+pH = 14
• pOH = -log[OH-]
• pH = -log[H3O+]
• pKa = -log(Ka)
• pKb = -log(Kb)
• Kw = [OH-] [H30+]

Question 4

TRUE OR FALSE

A partial dissociation of an acid is indicated by a SINGLE arrow

Answer 4

FALSE

Partial dissociation is indicated by DOUBLE ARROWS.

Question 5

Acidic drugs solubility equation

Answer 5

pH - pKa = log(S-S0/S0)

Question 6

Basic drug solubility equation

Answer 6

pH - pKa = log(S0/S-S0)

Question 7

S_0

Answer 7

The solubility of undissociated species a.k.a [HA]

Question 8

S

Answer 8

The total saturation solubility of a drug

Question 9

Henderson-Hasselbalch equation

Answer 9

pH = pKa + log [base]/[acid]

Question 10

Percentage ionisation

Answer 10

% ionisation = ( X / [HA]) X 100

• [HA] = undissociated species
• X= ionised species

Question 11

Kp

Answer 11

The equilibrium constant in respect to partial pressure.

Question 12

Noyes-Whitney equation

Answer 12

dm/dt = DA (Cs - C / h)

• D = diffusion coefficient
• A = Surface area
• Cs-C/H = Concentration gradient across the diffusion layer
• dm/dt = dissolution rate

Question 13

Stokes-Einstein equation

Answer 13

D = RT / 6π η a N_a
* η = Viscosity of the medium
* a = Molecular radius
* Na= Avogadros constant (6.02x10^23 mol-1)

Question 14

Fick’s law

Answer 14

J = -D (dC/dx)
* J = Rate of solute transfer per (unit area)
* dC/dX = Concentration gradient of solute