Difference between revisions of "Melting Point"
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: Adding [[salt]] to [[ice]] can lower its '''melting point''', causing it to [[melting|melt]] at a lower [[temperature]]. | : Adding [[salt]] to [[ice]] can lower its '''melting point''', causing it to [[melting|melt]] at a lower [[temperature]]. | ||
: [[Transition Metal]]s generally have very high '''melting points''', except for [[Mercury (Element)|Mercury]] which is [[liquid]] at [[Room Temperature|room temperature]]. | : [[Transition Metal]]s generally have very high '''melting points''', except for [[Mercury (Element)|Mercury]] which is [[liquid]] at [[Room Temperature|room temperature]]. | ||
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| + | ===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]]. | ||
Revision as of 10:58, 23 January 2019
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.