what is chromatography used for?
to separate individual components from a mixture of substances
what do all forms of chromatography have?
stationary phase
mobile phase
what is the stationary phase?
it does not move and is normally a solid or a liquid supported on a solid
what is the mobile phase?
it does move and is normally a liquid or a gas
what does thin layer chromatography use?
a TLC plate coated with a thin layer of a solid adsorbent substance
what is the TLC plate?
usually a plastic sheet or glass
what is the solid adsorbent substance for TLC?
silica
what is the stationary phase in TLC?
adsorbent
what do the different components in the mixture have for TLC?
different affinities for the adsorbent
they bind with differing strengths to its surface
define adsorption
the process by which solid silica holds different substances in the mixture to its surface
how are TLC analysed?
calculating the value for the retention factor for each component
what is the Rf value formula?
distance moved by the component/ distance moved by the solvent front
what is gas chromatography useful for?
separating and identifying volatile organic compounds present in a mixture
what is the stationary phase in gas chromatography?
a high boiling liquid adsorbed onto an inert solid support
what is the mobile phase in gas chromatography?
an inert carrier gas such as helium or neon
what is the process of gas chromatography?
a small amount of volatile mixture is injected into the apparatus
mobile gas carrier carries the components in the sample through the capillary column which contains the liquid stationary phase absorbed onto the solid support
the components slow down as they interact with the liquid stationary phase inside the column
how are the components of the mixture separated in a gas chromatogram?
depending on their solubility in the liquid stationary phase
define retention time
time taken for each component to travel through the column
what is each component detected as on the gas chromatogram?
a peak
what are the two pieces of information that can be obtained from a gas chromatogram?
retention times can be used to identify the components present in the sample by comparing these to retention times for known components
peak integrations can be used to determine the concentrations of components in the sample
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25.1 introducing benzene13
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25.2 electrophilic substitution reactions of benzene18
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25.3 the chemistry in phenol17
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25.4 directing groups16
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18.1 orders, rate equations and rate constants6
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18.2 concentration-time graphs13
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18.3 rate-concentration graphs and initial rates5
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26.1 carbonyl compounds18
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26.2 identifying aldehydes and ketones7
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26.3 carboxylic acids11
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26.4 carboxylic acid derivatives31
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19.1 the equilibrium constant Kc part 24
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19.2 the equilibrium constant Kp10
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19.3 controlling the position of equilibrium12
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27.1 amines25
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20.1 brønsted-lowry acid and bases6
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20.2 pH scale and strong acids6
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20.3 the acid dissociation constant Ka13
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20.4 pH of weak acids8
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20.5 pH and strong bases6
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21.1 buffer solutions13
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21.2 buffer solutions in the body7
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21.3 neutralisation11
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22.1 lattice enthalpy10
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27.2 amino acids, amides and chirality12
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27.3 condensation polymers7
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29.1 chromatography and functional groups analysis20
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29.2 NMR spectroscopy8
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29.3 Carbon-13 NMR spectroscopy3
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22.2 enthalpy changes in solution10
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22.3 factors affecting lattice enthalpy and hydration9
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22.4 entropy13
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22.5 free energy9
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23.1 redox reactions5
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23.2 manganate (VII) redox titrations2
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23.3 iodine/thiosulfate redox titrations5
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23.4 electrode potentials22
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23.5 predictions from electrode potentials5
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23.6 storage and fuel cells14
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24.1 d-block elements16
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24.2 formation and shapes of complex ions14
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24.3 stereoisomerism in complex ions13
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24.4 ligand substitution and precipitation37
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24.5 redox and qualitative analysis13
