2,903
edits
Changes
Pure
,no edit summary
: The opposite of a [[pure]] [[substance]] would be a [[mixture]] of [[substance]]s.
: A [[substance]] can be [[pure]] because it is made of only one [[element]] or it can be [[pure]] because it is made of only one [[compound]].
: The word [[pure]] is often used in food adverts to mean there is only one ingredient, eg [[pure]] orange juice contains only oranges, but most people confuse it for meaning something that is healthy, natural or good. Be careful not to confuse this for the real meaning of [[pure]].
===Examples===
|-
| style="height:20px; width:200px; text-align:center;" |[[Pure]] [[Gold]] is a [[solid]] made of only [[Gold]] [[atom]]s.
| style="height:20px; width:200px; text-align:center;" |[[Pure]] [[Mercury (Element)|Mercury]] is a [[Liquid]] made of only [[Mercury (Element)|Mercury]] [[atom]]s.
| style="height:20px; width:200px; text-align:center;" |[[Pure]] [[Oxygen]] is a [[gas]] made of only [[Oxygen]] [[atom]]s.
|}
| style="height:20px; width:200px; text-align:center;" |[[Pure]] [[Carbon Dioxide]] is a [[gas]] made of only [[Carbon Dioxide]] [[molecule]]s.
|}
==Key Stage 4==
===Meaning===
A [[pure]] [[substance]] is one that contains only one type of [[chemical]].
===About Purity===
: [[Pure]] does NOT mean good, healthy or natural.
: '''Purity''' is important for ensuring that when [[Chemical Reaction|reaction]]s take place there are no unwanted [[product]]s caused by the '''impurities'''.
: '''Impurities''' can change the [[property|properties]] of a [[substance]] such as its [[Melting Point|melting point]], [[Electrical Conductivity|electrical conductivity]] or [[Strength (Property)|strength]]. This means '''purity''' is essential when using [[substance]]s for certain [[application]]s where those [[property|properties]] important.
'''Purity''' may refer to:
*A '''pure''' [[element]] - A [[substance]] containing only one type of [[atom]].
*A '''pure''' [[compound]] - A [[substance]] containing only one [[chemical]] [[compound]].
===Detecting Purity===
: The '''purity''' of a sample can be determined by:
*Looking at its [[property|properties]] such as the [[Melting Point|melting point]] and [[Boiling Point|boiling point]]. If these are spread over a range of [[temperature]]s or different from the known values for the [[pure]] [[substance]] then the sample is not [[pure]]. For example to test if a sample of [[Water]] is [[pure]] it can be [[melting|melted]] from [[Ice]] and [[boiling|boiled]] from [[liquid]] [[Water]]. If the [[Melting Point|melting point]] is exactly 0°C and the [[Boiling Point|boiling point]] is exactly 100°C, then the [[Water]] is [[pure]].
*Using [[Chromatography]] to observe if a [[soluble]] [[solid]] is a [[mixture]] which [[Separating Mixtures|separate]]s on piece of [[Chromatography]] paper (there is more than one dot on the [[Chromatogram]]). For example a sample of coloured ink can be placed on some [[chromatography]] paper. Using a suitable [[solvent]] the [[solute]]s within the ink will move along the [[chromatography]] paper. If there is more than one [[solute]] then ink will split into more than one dot on the [[Chromatogram]].
===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=ad276ad49df77ab4b40ab4fd0fe10211 ''Purity, page 150, GCSE Combined Science; The Revision Guide, CGP, 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 ''Purity, page 198, 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 ''Purity, page 252, GCSE Chemistry, CGP, 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=9e29fad914244909903e5e93f8a01d217 ''Purity, page 86, GCSE Chemistry; 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 ''Purity, pages 180-181, GCSE Chemistry; Third Edition, Oxford University Press, AQA '']
====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 ''Impurities, page 26, Gateway GCSE Chemistry; The Revision Guide, CGP, 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 ''Impurities, page 98, 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 ''Impurities; in tap water, page 100, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR '']
:[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 ''Pure substances, pages 40-41, 48-49, 127, 199, Gateway GCSE Chemistry, Oxford, OCR '']