Mixing

Question 1

What is meant when a sample is homogeneous

Answer 1

it’s mixed in which the composition is uniform throughout

Question 2

Why is homogeneity important

Answer 2

so that each dose is identical, can be identically manufactured. Ensures api is +_ 5%

Question 3

What are the three types of mixtures

Answer 3

Positive, negative and neutral

Question 4

What is a positive mixture

Answer 4

A mixture in which the substances completely mix spontaneously. Energy is required to separate the substances. Water and ethanol

Question 5

What is a negative mixture

Answer 5

A mixture where the component do not stay mixed and separate spontaneously. Energy is required to keep the components mixed. E.g. water and oil.

Question 6

what does miscible mean

Answer 6

When a substance is able to mix and form a homogenous mixture

Question 7

What does immiscible mean

Answer 7

when substance is unable to mix and for and a homogeneous mixture

Question 8

What is a neutral mixture

Answer 8

a mixture in which the components do not separate or mix spontaneously. However energy is required to mix but components stay mixed,

Question 9

What are the the three ways of mixing liquids

Answer 9

Bulk, turbulent and molecular

Question 10

What is bulk mixing

Answer 10

redistributing large amounts of liquids. Occurs in a short period of time

Question 11

What is turbulent mixing

Answer 11

Mixing liquids by the redistribution of liquids by constantly changing velocity

Question 12

What is molecular mixing

Answer 12

mixing liquid Molecules by going down their concentration gradient

Question 13

What are the three types of solid mixing

Answer 13

convective, shear and diffuse

Question 14

What is convective mixing

Answer 14

redistribution of large amounts of particles

Question 15

What is shear mixing

Answer 15

velocity difference between layers cause them to slide over each other

Question 16

What is diffuse mixing

Answer 16

particles move from a high concentration into a low where there are air particles.

Question 17

What are the two types of mixtures

Answer 17

random and perfect

Question 18

Why is random mixture the best Attainable mixture

Answer 18

the probability of selecting a specific particle is the same throughout the whole mixture.

Question 19

What is the equation used to determine if a mixture is adequate

Answer 19

σR = √p(1-p)/N
σR= theoretical standard deviation of a random mixture
P=proportion of drug in mixer
N= total number of particles in the mixture

Question 20

How is the σR used to determine if a mixture is adequate

Answer 20

σ/σR.
σR= theoretical standard deviation of mixture
σ= sample standard deviation of mixture
>1 then not mixed properly
=1 then adequate mixture
<1 mixed too much, is lax

Question 21

What is the reverse process of mixing

Answer 21

segregation

Question 22

What is the difference between segregation and demixing

Answer 22

demixing is unwanted separation of a mixture while segregation is intended.

Question 23

What properties will allow easier segregation

Answer 23

particles are different size and density and if they’re spherical

Question 24

What are the three methods of segregation

Answer 24

Percolation, trajectory and elutriation

Question 25

What is percolation segregation

Answer 25

when smaller particles are serrated using voids.

Question 26

What is trajectory separation

Answer 26

when particles are allowed to flow out of a tube. Larger particle go further as they’re heavier so have more momentum

Question 27

What is elutriation segregation

Answer 27

When the least dense solids end up on top after movement stops.

Question 28

How to reduce segregation

Answer 28

Minimise vibrations, particles are the same size and density