Tutorial 9: buffer capacity

Question 1

give different names buffer capacity goes by

Answer 1

buffer efficiency, buffer value, buffer index

Question 2

T or F:
pharmaceutical solutions are buffered to a low capacity

Answer 2

truey wuey

Question 3

T or F:
pharmaceutical solutions are buffered to a high capacity

Answer 3

falsy
low capacity

Question 4

scientific term:
the magnitude of the resistance of a buffer to pH changes

Answer 4

buffer capacity (β)

Question 5

T or F:
boric acid is suitable for eye preparations but not for IV injections

Answer 5

truey wuey

Question 6

T or F:
boric acid is suitable for IV injections but not for eye preparations

Answer 6

falsy
the opposite

Question 6

_____ and _____ buffers are incompatible with any compounds including the salts of silver, iron, magnesium and zinc

Answer 6

borate and phosphate

Question 7

borate and phosphate buffers are incompatible with any compounds including the salts of__,___,___ and ___

Answer 7

silver, iron, magnesium and zinc

Question 8

which salts are borate and phosphate buffers incompatible with?

Answer 8

zinc, silver, magnesium and iron salts

Question 9

____ buffers form complexes with excipients like glycerol and carbohydrates

Answer 9

borate

Question 10

borate buffers form complexes with excipients like ___ and ____

Answer 10

glycerol, carbohydrates

Question 11

T or F:
borate buffers are compatible with excipients like glycerol and carbohydrates

Answer 11

falsy
they form complexes with them, not compatible

Question 12

how is blood pH maintained as 7.4?

Answer 12

with the help of primary buffers in blood plasma and secondary buffers (hemoglobin) in erythrocytes

Question 13

what are the two buffer systems in blood plasma?

Answer 13

carbonic acid/bicarbonate and phosphoric acid/sodium phosphate

Question 14

what are the two buffer systems in erythrocytes?

Answer 14

hemoglobin/oxyhemoglobin and phosphoric acid/sodium phosphate

Question 15

T or F:
lachrymal fluid has great buffer capacity

Answer 15

truey

Question 16

T or F:
β is proportional to the concentration of buffer components added to the solution

Answer 16

truey

Question 17

T or F:
β doesn’t necessarily depend on the ratio of its components

Answer 17

falsy
it is proportional to the conc of its components

Question 18

T or F:
β depends on the pKa of weak acid or base

Answer 18

truey

Question 19

what does β depend on?

Answer 19

pKa of acid or base
conc of its components
volume of medium

Question 20

T or F:
β is a fixed value

Answer 20

falsy

Question 20

the ___ the change in pH change in a solution after adding base/acid, the greater the buffer capacity

Answer 20

lower/smaller

Question 21

T or F:
β will increase with external addition of acid or base

Answer 21

falsy
it will decrease because the added acid/base will consume buffer therefore lower the β

Question 22

T or F:
β will decrease with external addition of acid or base

Answer 22

truey because the added acid/salt will consume more buffer

Question 23

T or F: the final pH of the buffer is more important than the capacity

Answer 23

falsy β and the volume used in relation to the medium's volume aremore important

Question 24

how can β be expressed in terms of amount of stronk acid or base added to change the pH?

Answer 24

β equals the amount of stronk acid or base in moles of H+ or OH- per liter, to bring pH down by one unit

Question 25

when will a buffer have maximum capacity

Answer 25

when pKa of weak acid or base is closed to the desired pH or the ratio of (salt)/acid equals 1 when log (ratio) equals 0

Question 26

T or F: all buffers work best at the same pH

Answer 26

falsy each buffer works best at a certain pH

Question 27

the higher the difference between the pH of the solution and pKa, the ___ the capacity

Answer 27

lower

Question 28

T or F: the higher the difference between the pH of the solution and pKa, the higher the capacity

Answer 28

falsy the lower

Question 29

T or F: he lower the difference between the pH of the solution and pKa, the higher the capacity

Answer 29

truey weuy

Question 30

how many times can you dilute lachrymal fluid before an alteration in pH is noticed?

Answer 30

15 times

Question 31

T or F: how much a solution can be diluted until pH changes is known as buffer capacity or buffer value

Answer 31

falsy that's dilution value

Question 32

scientific term: how much a solution can be diluted until pH changes

Answer 32

dilution value

Question 33

__ in the air makes makes conjunctival fluid more acidic

Answer 33

CO2

Question 34

for eye drops, irritation and discomfort and flow of tears will occur if the pH drops below ___ or above ___

Answer 34

6.6, 9

Question 35

T or F: for eye drops, irritation and discomfort and flow of tears will occur if the pH drops below 6.9 or above 7.8

Answer 35

falsy 6.6, 9.

Question 36

phosphate buffer - boric acid soltuion which one causes discomfort in the eyes?

Answer 36

phosphate buffer

Question 37

which buffer is most suitable for the eyes and what is its pH?

Answer 37

boric acid solution. pH of 5

Question 38

T or F: boric acid causes irritation in the eyes because its pH is 5

Answer 38

falsy it causes no discomfort

Question 39

T or F: phosphate buffer causes irritation in the eyes

Answer 39

truey

Question 40

why is boric acid more suitable for the eyes than phosphate buffer?

Answer 40

1. boric acid has a lower buffer capacity 2. the physiological response to various ion species

Question 41

T or F: Ophthalmic solutions are usually not buffered or buffered to a low capacity

Answer 41

falsy this applies on parenteral solutions

Question 42

why are parenteral solutions not buffered or buffered to a low capacity?

Answer 42

becuase blood buffers will do their job and bring them within the stable pH range

Question 43

what is the normal urine pH for an adult?

Answer 43

6

Question 44

what is the range of urine pH?

Answer 44

4.8-7.8

Question 45

what does the kidney do when pH of urine is below normal values?

Answer 45

retain hydrogen ions

Question 46

what does the kidney do when pH of urine is above normal values?

Answer 46

it will excrete hydrogen ions to bring the pH to its normal range

Question 47

T or F: When the urine pH is below normal values, the kidney will excrete hydrogen ions to bring pH back to normal

Answer 47

falsy kidney does this when pH of urine is higher than normal

Question 48

T or F: hydrogen ions are retained by the kidneys and when the urine pH is above 7.4

Answer 48

truey

Question 49

T or F: hydrogen ions are retained by the kidneys and when the urine pH is below 4.8

Answer 49

falsy it will retain H+ when pH is above 7.4

Question 50

T or F: some food and drinks can alter urine pH

Answer 50

truey

Question 51

why are strong acids and bases able to act as buffers?

Answer 51

because of their high conc of H+ and OH- ions

Question 52

why is KCL added to HCL buffers even though they don't participate in the buffering?

Answer 52

they are added to adjust ionic strength

Question 52

T or F: potassium chloride is added to HCL buffers to help in buffering

Answer 52

no it doesn't help in buffering but it adjusts ionic strength

Question 53

the pH of the stomach ranges from __ to __ depending on the presence of food in it

Answer 53

1, 4

Question 54

the pH of the stomach ranges from 1to 4 depending on ___

Answer 54

whether or not there is food in it

Question 55

what does the gastric (digestive) fluid made of?

Answer 55

HCL, KCL and NaCl

Question 56

what does the acidic environment of the stomach aid in?

Answer 56

digestion + prevention of infection

Question 57

T or F: the higher the capacity the higher the irritation

Answer 57

truey

Question 58

T or F: the lower the capacity the higher the irritation

Answer 58

falsy the lower the irritation

Question 59

what happens if we use a low capacity buffer on the eyes but add a large volume?

Answer 59

irritation, because the higher the volume of pharmaceutical solution used the higher the irritation

Question 60

to avoid irritation, the volume of pharmaceutical solution must be low and has a high capacity

Answer 60

falsy should have low volume and low capacity

Question 61

to avoid irritation, the volume of pharmaceutical solution must be low and has a low capacity

Answer 61

Truey

Question 62

T or F: to avoid irritation, the volume of pharmaceutical solution must be low and has a low capacity whereas physiological fluid should have high volume and high capacity

Answer 62

SO TRUEY

Question 63

to avoid irritation, what should be the relationship between capacity and volume of pharmaceutical solution (a) and physiological fluid (b)?

Answer 63

(a) must have low V low capacity (b) must have high V high capacity

Question 64

T or F; ionized forms of drugs can easily penetrate biological membranes

Answer 64

falsy unionized

Question 64

T or F: ionized forms of drugs tend to stay in the aqueous environment in the body

Answer 64

truey

Question 65

T or F: unionized forms of drugs can easily penetrate biological membranes

Answer 65

truey

Question 66

why can unionized forms of drugs penetrate biological membranes?

Answer 66

because BM are lipid, unionized drugs are more lipid soluble while unionized forms are water soluble

Question 66

T or F: it is important that the drug will be in ionized form in the part of the body where it is placed to be absorbed.

Answer 66

falsy must be unionized

Question 67

it is important that the drug will be in ___ form in the part of the body where it is placed to be absorbed.

Answer 67

unionized