Acid-base Theory, pH, pKa & pKb- go over it as coculations are needed

Question 1

Weak Organic Acids

Answer 1

Aspirin, Ibuprofen, Diclofenac, Benzylpenicillin

Question 2

Weak Organic Bases

Answer 2

Morphine, procaine, Benzocaine, Chloramphenicol

Question 3

their salt

Answer 3

Ephedrine hydrochloride, sodium ibuprofen, potassium diclofenac

Question 4

A Lowry-Brønsted ACID

Answer 4

is a proton DONOR

strong acid full ionisation
weak acids partial ionisation

Question 5

A Lowry-Brønsted BASE

Answer 5

is a proton ACCEPTOR

Question 6

ampholyte

Answer 6

act as an acid or base

is called an AMPHOLYTE
and is said to be AMPHOTERIC in nature.

Question 7

Acid1 /Base1 and Acid2/Base2 in such an equilibrium are

Answer 7

known as Lowry-Brønsted conjugate acid-base pairs

Question 8

The Dissociation of Weak Acids

Answer 8

The dissociation of a WEAK ACID in aqueous conditions can be represented as follows: HA + H2O A- + H3O+
The equilibrium constant (for a weak acid) may be expressed as follows:

    [H3O+][A-]  Ka = ----------------
	[HA]                         

 pKa = - log Ka

The lower the pKa-the stronger the acid

Question 9

The Dissociation of Weak Bases

Answer 9

The dissociation of a WEAK BASE in aqueous conditions can be represented as follows: B + H2O OH- + BH+

The equilibrium constant (for a weak base) may be expressed as follows:

[OH-] [BH+]	                      Kb = -------------
	[B]		              
                                 pKb = - log Kb

The lower the pKb-the stronger the base

Question 10

The pKa and pKb values of a conjugate acid-base pair are linked by the following expression

Answer 10

pKa + pKb = pKw

Where pKw is the negative log of the dissociation constant for water (Kw).

At 25oC : pKw = 14.00

Question 11

Amphoteric electrolytes

Answer 11

are electrolytes which can function as either acids or bases ( amino acids and proteins).
Example: Over the pH range 3-9, glycine exists in solution predominantly in the form +NH3CH2COO-.
Such a structure, having both positive and negative charges on the same molecule, is referred to as “ZWITTERION”:

acidic conditions becomes main base

basic conditions main molecule becomes acidic

Question 12

capable of donating or accepting more than one proton are

Answer 12

polyprotic

Question 13

pH-Dissociation profiles for weak acids and bases

Answer 13

pKa = pH at which 50 % of species are ionised.

At  2 pH units away from pKa weak electrolytes are completely dissociated/undissociated

The acidic drug is completely unionised at PHs up to 2 units below its PKA and virtually completely ionised at PH greater than 2 units above its Pka

Question 14

The Conjugated Base of a Strong Acid

Answer 14

is a weak

Question 15

The Conjugated Acid of a Strong Base

Answer 15

is a Weak Acid

Question 16

Electrolyte

Answer 16

is a compound that is ionised in solution.

Electrolytes yield ions when dissolved in water and therefore could conduct an electric current through solution.

Question 17

Non-electrolytes

Answer 17

are substances that do not yield ions when dissolved in water and therefore do not conduct an electric current through the solution.

Examples of non-electrolytes are:
- Sucrose
- Glycerin
- Naphtalene
- Urea
- Steroids

Question 18

weak acid + strong base

Answer 18

will make a salt and the addition of water will make salt and oh-

Question 19

Buffers

Answer 19

Resistant to changes in pH.

Usually a mixture of a weak acid and its salt (conjugate base), or of a weak base and its salt (conjugate acid).

Question 20

common ion effect

Answer 20

is a decrease in the solubility of an ionic compound as a result of the addition of a common ion

addition of an equal
concentration of a salt with a common ion

Question 21

Buffer Capacity -

Answer 21

Also known as “buffer efficiency”, “buffer index” and “buffer value

is defined as the ratio of the increment of strong base (or acid) to the small change in pH brought about by this addition.

Question 22

HH EQN- weak acids

Question 23

HH EQN- weak base

Question 24

HH EQN buffer equation for weak base

Question 25

HH EQN buffer equation for weak acid