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→About Chromatography
: When more than one [[solute]] is [[dissolve]]d in a [[solvent]] [[chromatography]] can be used to [[Separating Mixtures|separate]] them.
: [[Chromatography]] [[experiment]]s are often done with colourful [[solute]]s which can be seen easily.
: [[Chromatography]] works because different [[solute]]s [[diffusion|diffuse]] at different rates.
{| class="wikitable"
|-
|[[File:ChromatographyExperimentDiagram.png|center|500px]]
|-
| style="height:20px; width:200px500px; text-align:centerleft;" |: 1. #Draw a pencil line across a piece of [[chromatograph]] paper.: 2. #Place a dot of ink on the line.: 3. #Hang the paper so that it touches the water but do not let the ink go below the water line.: 4. #Allow the water to rise up the paper.: 5. #Once the water stops rising up the paper observe the ink to see if any colours have separated.
|}
==Key Stage 4==
===Meaning===
[[Chromatography]] is a technique used to [[Separating Mixtures|separate]] and identify different [[solute]]s found in a [[solution]].
===About Chromatography===
'''Chromatography''' can be used for:
*[[Separating Mixtures|Separating]] and identifying two or more [[solute]]s from a [[solution]].
*Identifying [[pure]] from [[impure]] [[substance]]s.
'''Chromatography''' cannot be used for:
*[[Separating Mixtures|Separating]] separating [[liquid]]s in [[solution]] - [[Fractional Distillation]]
*[[Separating Mixtures|Separating]] an [[insoluble]] [[solid]] from a [[soluble]] [[solid]] - [[Filtration]]
*[[Separating Mixtures|Separating]] [[solute]]s from a [[solvent]] in [[solution]]. - [[Evaporation of Solutions|Evaporation (Crystallisation)]] or [[Distillation]].
: [[Chromatography]] relies on different [[chemical]]s experiencing different [[force]]s of [[attraction]] between the [[solvent]] used and the [[chromatography]] paper. The [[solvent]] is referred to as the '[[Mobile Phase|mobile phase]]' and acts to carry the [[chemical]] along as the [[solvent]] moves through the [[chromatography]] paper (mobile because it makes the chemical move). The [[chromatography]] paper is referred to as the '[[Stationary Phase|stationary phase]]' and acts to hold the [[chemical]]s in place (stationary because it stops them from moving).
: Each [[chemical]] has a [[Retention Factor|Retention Factor (R<sub>f</sub> number)]] which is a [[ratio]] of how far the [[chemical]] moves along the paper compared to how far the [[solvent]] moves along the paper. The larger this [[Retention Factor]] the greater the [[force]] of [[attraction]] experienced by the [[chemical]] to the paper. The [[chemical]] is 'retained' in place.
: [[Retention Factor|R<sub>f</sub>]] numbers are unique to each [[chemical]] and can be used to [[Separating Mixtures|separate]] and identify the [[chemical]].
===Method===
====Detecting Purity====
#Take a piece of [[chromatography]] paper of [[width]] 2cm and [[height]] 10cm.
#Using a ruler draw a line with pencil across the [[width]] 1cm up from the end.
#Add a dot of the unknown sample on the pencil line.
#Suspend the [[chromatography]] paper in a suitable [[solvent]] just below the pencil line with most of the paper above the [[solvent]].
#Wait until the [[solvent]] stops rising up the paper.
#If there is more than one dot on the [[Chromatogram]] then the [[substance]] was [[Pure|impure]]. If there is only one dot on the [[Chromatogram]] the [[substance]] was [[pure]].
====Identifying Chemicals by Comparison====
The [[chromatogram]] from an [[experiment]] can be compared against [[chromatogram]]s of known [[chemical]]s to identify the [[chemical]]s in the original sample.
#Take a piece of [[chromatography]] paper of [[width]] 2cm and [[height]] 10cm.
#Using a ruler draw a line with pencil across the [[width]] 1cm up from the end.
#Add a dot of the unknown sample on the pencil line.
#Suspend the [[chromatography]] paper in a suitable [[solvent]] just below the pencil line with most of the paper above the [[solvent]].
#Wait until the [[solvent]] stops rising up the paper.
#Compare this [[chromatogram]] to [[chromatogram]]s of known [[chemical]]s.
====Identifying Chemicals by R<sub>f</sub> Number====
The [[Retention Factor|R<sub>f</sub>]] values for a variety of [[chemical]]s are known. By comparing the [[Retention Factor|R<sub>f</sub>]] values from an [[experiment]] to the known values of different [[chemical]]s then the [[chemical]]s in the [[experiment]] may be identified.
#Take a piece of [[chromatography]] paper of [[width]] 2cm and [[height]] 10cm.
#Using a ruler draw a line with pencil across the [[width]] 1cm up from the end.
#Add a dot of the unknown sample on the pencil line.
#Suspend the [[chromatography]] paper in a suitable [[solvent]] just below the pencil line with most of the paper above the [[solvent]].
#Wait until the [[solvent]] stops rising up the paper.
#Use a ruler to measure the distance that the [[solvent]] has traveled up the paper.
#Use a ruler to measure the distance that the [[chemical]] has traveled up the paper.
#Use the following equation to find the [[Retention Factor]]:
:<math>R_f = \frac{d_c}{d_s}</math>
:Where:
:R<sub>f</sub> = [[Retention Factor]]
:d<sub>c</sub> = distance moved by the [[chemical]]
:d<sub>s</sub> = distance moved by the [[solvent]]
===References===
====AQA====
:[https://www.amazon.co.uk/gp/product/1782945598/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945598&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe09771 ''Chromatography, pages 101, 151, 152, GCSE Combined Science; The Revision Guide, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/0198359381/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359381&linkCode=as2&tag=nrjc-21&linkId=47c8d1ae58d8b3a5e2094cd447154558 ''Chromatography, pages 10-11, 182-183, GCSE Chemistry; Third Edition, Oxford University Press, AQA '']
:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Chromatography, pages 137, 139, GCSE Combined Science Trilogy 1, Hodder, AQA '']
:[https://www.amazon.co.uk/gp/product/1471851362/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851362&linkCode=as2&tag=nrjc-21&linkId=7d78d70a2044ee9982dae010c94af92a ''Chromatography, pages 157-9, GCSE Combined Science Trilogy 2, Hodder, AQA '']
:[https://www.amazon.co.uk/gp/product/1782945571/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945571&linkCode=as2&tag=nrjc-21&linkId=9e29fad914244909903e5e93f8a01d81 ''Chromatography, pages 16, 87, GCSE Chemistry; The Revision Guide, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/0008158762/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158762&linkCode=as2&tag=nrjc-21&linkId=a0fffa35b3ea49a63404f6704e0df7cc ''Chromatography, pages 18, 265, 286-7, GCSE Chemistry; Student Book, Collins, AQA '']
:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Chromatography, pages 24, 205-6, 213, GCSE Chemistry, Hodder, AQA '']
:[https://www.amazon.co.uk/gp/product/178294639X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294639X&linkCode=as2&tag=nrjc-21&linkId=51599bb45a2bfaf7c1b6a978b2ca2616 ''Chromatography, pages 35, 36, 200-202, GCSE Combined Science Trilogy; Chemistry, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/1782945962/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945962&linkCode=as2&tag=nrjc-21&linkId=476bb5c8d1dfb5c08ac81b6d4d1c98d8 ''Chromatography, pages 35, 36, 254-256, GCSE Chemistry, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/0008158762/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158762&linkCode=as2&tag=nrjc-21&linkId=a0fffa35b3ea49a63404f6704e0df7cc ''Chromatography; gas-liquid, pages 270, 282, GCSE Chemistry; Student Book, Collins, AQA '']
:[https://www.amazon.co.uk/gp/product/0008158762/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158762&linkCode=as2&tag=nrjc-21&linkId=a0fffa35b3ea49a63404f6704e0df7cc ''Chromatography; paper, pages 262-3, 268-71, GCSE Chemistry; Student Book, Collins, AQA '']
:[https://www.amazon.co.uk/gp/product/0008158762/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158762&linkCode=as2&tag=nrjc-21&linkId=a0fffa35b3ea49a63404f6704e0df7cc ''Chromatography; thin layer, pages 263, 269, GCSE Chemistry; Student Book, Collins, AQA '']
====Edexcel====
:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Chromatography, page 152, GCSE Combined Science, Pearson Edexcel '']
:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Chromatography, page 8, GCSE Chemistry, Pearson, Edexcel '']
:[https://www.amazon.co.uk/gp/product/1782945741/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945741&linkCode=as2&tag=nrjc-21&linkId=30da4f2178da182547b62a7329d13b57 ''Chromatography, pages 102, 103, GCSE Combined Science; The Revision Guide, CGP, Edexcel '']
:[https://www.amazon.co.uk/gp/product/1782948147/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948147&linkCode=as2&tag=nrjc-21&linkId=f63dcd8345f4e49c717b39a228a36c7c ''Chromatography, pages 107-111, GCSE Chemistry, CGP, Edexcel '']
:[https://www.amazon.co.uk/gp/product/1782945725/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945725&linkCode=as2&tag=nrjc-21&linkId=694be7494de75af3349537d34e13f7f0 ''Chromatography, pages 39, 40, GCSE Chemistry; The Revision Guide, CGP, Edexcel '']
:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Chromatography; paper 8-9, GCSE Chemistry, Pearson, Edexcel '']
:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Chromatography; paper, pages 152-153, GCSE Combined Science, Pearson Edexcel '']
====OCR====
:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Chromatography, pages 102, 103, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']
:[https://www.amazon.co.uk/gp/product/1782945679/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945679&linkCode=as2&tag=nrjc-21&linkId=a2db42f7b4bdf10cafaafa3bb9120940 ''Chromatography, pages 29, 30, 61, GCSE Chemistry; The Revision Guide, CGP, OCR Gateway '']
:[https://www.amazon.co.uk/gp/product/0198359829/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359829&linkCode=as2&tag=nrjc-21&linkId=90e8d7b4f039d53035238fa0320fe00b ''Chromatography, pages 46-49, 153, 268-269, Gateway GCSE Chemistry, Oxford, OCR '']