lab quiz 1-2

Question 1

sorption

Answer 1

2 processes. Adsorption and absorption.

Question 2

absorption

Answer 2

molecules cross the membrane interface to enter the interior of the cell

important physiological process

Question 3

adsorption

Answer 3

when the molecules (adsorbate) attach to a solid surface (adsorbent/interface).

Question 4

adsorbate

Answer 4

is a liquid solute in a solution or gas which is being adsorbed

Question 5

solid surface in adsorption (adsorbent)

Answer 5

called interface

Question 6

physical adsorption (physisorption)

Answer 6

is a physical process where the adsorbate is held to the surface of the solid by WEAK VAN DER WAALS forces. this adsorbate-adsorbent interaction can easily be broken by changes in temp and pH and adsorbent easily regenerated (process or regeneration is called desorption).

Question 7

at equilbruim adsorption and desorption are at constant rate

Answer 7

so concentration of the adsorbate is constant

Question 8

chemical adsorption

Answer 8

is a chemical process where a chemical bond (ionic/covalent) is formed between adsorbent and adsorbate. Stronger adsorbate and adsorbent interactions more challenging to make desorption

Question 9

Adsorbents are typically classified into three types

Answer 9

adsorbents- used for decoloring and refining food for pharmacological effects.

1. hydrophilic and polar oxygen containing compounds, like silica gel
2. non-polar carbon containing compounds, such as activated carbon and graphite
3. porous polymer matrix with non-polar and polar f-groups

Question 10

activated charoal

Answer 10

common adsorbent used in pharmacy and medicine. it can adsorb wide range of adsorbates, it is used to treat toxicity due to oral drug indigestion.

the drug gets absorbed by charcoal and this reduces the systemic absorption into GI tract

Question 11

the amount of absorbate adsorbed is

Answer 11

dependent on the adsorbent qt size, and grade (particle size and quality )

Question 12

the MOLES of adsorbate adsorbed by A GRAM of adsorbent

Answer 12

is used to express the effectiveness of adsorbent for specific adsorbate.

Question 13

factors that influence adsorption

Answer 13

temperature
layer
type of adsorption
concentration of adsorbate
quantity of adsorbent

Question 14

as temperature increases

Answer 14

adsorption will DECREASE (TEMP AND ADSORPTION INVERSALLY PROPORTIONAL)

Question 15

EXTENT OF adsorption depends on 3 factors

Answer 15

1. capacity- SA of adsorbent and receptor sites on adsorbate

2.affinity- properties of adsorbent and adsorbate

3. equilibrium conditions (temp and conc of the adsorbate)

Question 16

quantity of adsorbate

by unit weight of adsorbent

at equilibrium conc

Answer 16

x

x/m and m

C

as we increase the conc the x/m will increase linearly and increase adsorption
y=mx +c

Question 17

x/m =kC

Question 18

freundlich empirical eq

Answer 18

(i) for adsorption of gases (as a mono layer) to solids. Log values are used to linearize the equation
(ii) log values, the equation of the curve is modified to an equation of a straight line

Question 19

At low pressure, the extent of adsorption (x/m)

Answer 19

varies linearly with the gas pressure

Question 20

At moderate pressure, (x/m)

Answer 20

varies exponentially to gas pressure

Question 21

At high pressure, (x/m)

Answer 21

is independent of gas pressure

Question 22

Langmuir isotherm is based on several assumptions.

Answer 22

1. Adsorption is a second order reaction (dependent on adsorbent and adsorbate concentration.
2. The surface of the adsorbent is uniform and has a fixed number of active (adsorbent) sites.

3.Adsorbate is adsorbed at the surface as a single monolayer. molecules of adsorbate do not deposit on each other

4. One adsorbate molecule is adsorbed to only one single active site.
5. The adsorption is random and non-specific physio-adsorption via weak forces (van der Waals).
6. equilibrium, the fraction of the active sites θ is occupied by adsorbed molecules fraction of free active sites is 1-θ. This value remains constant for the specific temperature and concentration.
7. Adsorbed molecules do not interact with each other or with other molecules in the system.

Question 23

SPECIFIC AREA OF ADSORBENT

Answer 23

S = (N) x(Csa)/b

S = (Avogadro’s number x molecular cross-section of the adsorbate)/Langmuir constant

Greater the value better the adsorption capacity of the adsorbent.

Question 24

Adsorption is useful in treating oral drug overdose.

Answer 24

true

Question 25

Alkaloid drugs and theophylline absorption in the GI tract are reduced by oral administration of

Answer 25

activated charcoal adsorbent. the drug is adsorbed to the charcoal and excreted in the feces.

Question 26

Citric acid is a triprotic acid (i.e. contains three ionizable hydrogen [H+} or 3 Eq/mole)

Question 27

Sodium hydroxide is a monobasic base (has one [OH-} or 1 Eq neutralizes one ionizable hydrogen [H+} ).

Question 28

Hence 3 moles (3 Eq) of sodium hydroxide neutralize 1 mole (3 Eq) of citric acid.

Question 29

Phenolpthalein (pKa 9.3) is used as pH indicator (color change: colorless to pink color) is used to detect the endpoint of the neutralization.

Question 30

Phenolpthalein (pKa 9.3) is used as pH indicator (color change: colorless to pink color) is used to detect the endpoint of the neutralization.

Question 31

Regression Analysis: Before performing the statistical analysis for goodness-of-fit, the experimental data should be evaluated for errors (calculations, techniques).

Answer 31

R-squared is a statistical measure of how close the data are to the fitted regression line. Linear regression calculates an equation that minimizes the distance between the fitted line and all of the data points. In general, the higher the R-squared, the better the model fits your data. R-squared is a useful measure that indicates how well the linear model fits a set of observations.

Question 32

Antacid

Answer 32

alkalizing formulations are prescribed when stomach acid to help increase pH (basic) and reduce acidity.

Question 33

suspensions

Answer 33

LIQUID FORMULATION, we have drug insoluble in a vehicle. 2 phase-solid and aq. Phase. Heterogeneous solution.

Question 34

We would prepare different forms

Answer 34

because of ppl would be children or who cannot swallow. The drug is insoluble; you can only use suspension, if the drug is not very stable. Over time the drug would settle. If the drug has small particle size then if it settles then this can cause interlocating and form a cake at the bottom, and the drug when shaken cannot disperse equally.

Question 35

Suspending agents

Answer 35

helps increase the viscosity of the soln, if you have a dilute soln the drug settles quickly. Viscosity agent helps increase the pore-ability AND redispersibility of the drug

Question 36

Titration

Answer 36

helps to understand the neutralization capacity of the suspension

Question 37

1 ml of preserve is 100 ml of suspension, so 60ml (formulation) is X= 0.6ml of preservative

Question 38

50x = 1mL of preservative can preserve 50 ml, so if we prepare 60ml of formulation we need to add 1.2ml

Question 39

fine powders

Answer 39

defluoccation decrease in wet-ability or caking higher surface energy and SA