Chromotography

Question 1

chromotograohy

Answer 1

a technique used to seperate the different substances present in a mixture

Question 2

all chromotograohy methods have a

Answer 2

1. a stationary phase, a medium which the sample can adsorb to 2. a mobile phase, where a solvent carries the sample over the stationary phase (deadsorbtion)

Question 3

what are the three different types of chromotography

Answer 3

papa\er chromotography, thin layer chromotography and HPLC (high pressure liquid chromotography)

Question 4

paper chromotograhy

Answer 4

uses high quality absorbent paper as the stationary phase, a small sample of the specific mixture is placed on the stationary phase and placed in a solvent

Question 5

thin-layer chromotograohyy

Answer 5

uses a thin layer of absorbent materials such as aluminium oxide, silica or cellulose, a small sample of the specific mixture is placed on the stationary phase and placed in a solvent

Question 6

the place where the sample is put is called the

Answer 6

origin

Question 7

the spread of colours on the stationary phase is called

Answer 7

chromatogram

Question 8

standards

Answer 8

used to determine the components in a mixture by containing a sample of known cehmicals on the same chromotogram as the inks own sample

Question 9

retention factor (Rf)

Answer 9

the distance each component has travelled compared to the solvent front, can then be compared to checmicals of lnown values under the same conditions

Question 10

equation to calculate rf

Answer 10

distance travelled by compound/distance travelled by solvent front

Question 11

variables that affect Rf

Answer 11

temperature, type of solvent and stationary phase

Question 12

HPLC

Answer 12

a chromotographyy technique that consists of a solid stationary phase which is tightly packed into a column (usually glass) annd a solvent acting as a mobile phase,

Question 13

which ideas dooes HPLC rely on

Answer 13

how well the stationary phase adsrobs to yje sample through a force of attraction and how well the mobile phase can dissolve the sample through desorption

Question 14

desorption

Answer 14

previously adsorbed substance is realesed from a surface into the mobile pahse

Question 15

the more strongly a compound bonds to a stationary phase

Answer 15

the slower the rate of movement of that compound over the stationary phase

Question 16

the more soluble a component is in the mobile phase

Answer 16

the faster it will move

Question 17

HPLC rf

Answer 17

the time that a component of the sample spends in the HPLC column, time taken to pass through stationary phase

Question 18

factors that influence Rf in HPLC

Answer 18

identitity and composition of the stationary and mobile phase, length and temp of column, S:A of stationary phase

Question 19

increased S:A of stationary phase effect

Answer 19

increased Rf as there arre more interactions between the component and stationary phase and therefore it will take longer to elute

Question 20

The area under a peak of a chromatogram shows

Answer 20

the concentration of the componenet when comparing to a standard

Question 21

steps in determining oncentration of components in HPLC

Answer 21

standard solutions are prepared and a fixed volume of each is injected into the instrument, the area under the peak of each solution is measured, a calibration graph is plotted using the results obtained from the standard solutions, tthe sample is injected and its peak area is measured, the samples concentration is determined using the calibration graph

Question 22

adsorption

Answer 22

adhering onto the solid stationary phase

Question 23

desorption

Answer 23

following adsorption, dissolving into the mobile phase

Question 24

qualitive analysis chromotography

Answer 24

the determination of the chemical composition of a sample

Question 25

quantitative analysis chromotography

Answer 25

analysing that allows us to meaure the amount of different chemical components

Question 26

low rf values means

Answer 26

tthe component moved the slowest/least distance