Difference between revisions of "Melting Point"
Line 13: | Line 13: | ||
===Detecting Purity=== | ===Detecting Purity=== | ||
: The [[Pure|purity]] of a sample can be determined by [[observing]] its [[Melting Point|melting point]]. If the [[Melting Point|melting point]] is 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]] which should happen at exactly 0°C if it does not then it is not [[pure]]. | : The [[Pure|purity]] of a sample can be determined by [[observing]] its [[Melting Point|melting point]]. If the [[Melting Point|melting point]] is 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]] which should happen at exactly 0°C if it does not then it is not [[pure]]. | ||
+ | |||
+ | ===References=== | ||
+ | ====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 ''Melting points, pages 36-37, 47, GCSE Chemistry; Third Edition, Oxford University Press, AQA ''] | ||
+ | :[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Melting points, pages 80-81, 84, GCSE Physics; Third Edition, Oxford University Press, 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 ''Melting points; alkali metals, page 26, GCSE Chemistry; Third Edition, Oxford University Press, 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 ''Melting points; halogens, page 28, GCSE Chemistry; Third Edition, Oxford University Press, 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 ''Melting points; purity analysis, pages 180-181, GCSE Chemistry; Third Edition, Oxford University Press, 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 ''Melting points; transition elements, page 32, GCSE Chemistry; Third Edition, Oxford University Press, AQA ''] |
Revision as of 11:41, 8 November 2019
Contents
Key Stage 4
Meaning
Melting point is the temperature at which a solid can become a liquid.
About Melting Points
- Different substances have different melting points.
- The melting point of a substance is determined by the strength of the bonds which hold the particles in fixed positions in a solid. The stronger the bonds the higher the melting point.
- When a substance is heated to its melting point it will remain at this constant temperature until all of the solid has melted.
- The melting point of pure water ice is 0°C or 273 Kelvin.
- Adding salt to ice can lower its melting point, causing it to melt at a lower temperature.
- Transition Metals generally have very high melting points, except for Mercury which is liquid at room temperature.
Detecting Purity
- The purity of a sample can be determined by observing its melting point. If the melting point is spread over a range of temperatures 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 melted from Ice which should happen at exactly 0°C if it does not then it is not pure.
References
AQA
- Melting points, pages 36-37, 47, GCSE Chemistry; Third Edition, Oxford University Press, AQA
- Melting points, pages 80-81, 84, GCSE Physics; Third Edition, Oxford University Press, AQA
- Melting points; alkali metals, page 26, GCSE Chemistry; Third Edition, Oxford University Press, AQA
- Melting points; halogens, page 28, GCSE Chemistry; Third Edition, Oxford University Press, AQA
- Melting points; purity analysis, pages 180-181, GCSE Chemistry; Third Edition, Oxford University Press, AQA
- Melting points; transition elements, page 32, GCSE Chemistry; Third Edition, Oxford University Press, AQA