melting point represents the exact temperature at which there is a change from solid to liquid state of a given substance.
Water is one of the most used elements to exemplify the melting point principle. For this substance in the solid state (ice) to take the form of liquid water, it needs to be exposed to a temperature of at least 0°C. Thus, the melting point of water is equal to 0°C.
However, obtaining the melting point serves to certify the purity of the substance under analysis, since the temperature has a variation greater than 1°C of difference from the defined standard value for that element, then the substance is not pure.
For example, if the melting point of an analyzed water sample was not 0°C but 1.2°C, then this substance was not in its full purity state.
The melting point also has the same temperature as when a substance is solidifies, that is, it goes from a liquid to a solid state.
Melting point and boiling point
As said, the melting point represents the passage from solid to liquid state. On the other hand, the so-called boiling point is the
Exact temperature at which the liquid goes to the gaseous state.Following the same example as water, just as its melting point is 0ºC, its boiling point (with pressure at sea level, that is, 1 atm) is 100ºC. As can be seen, the boiling point is variable, depending on the level of ambient pressure, for example.
Learn more about Boiling.
However, it is worth remembering that each element has a different melting point, according to their respective chemical structures. Likewise, the pressure level where this substance is exposed also helps to obtain a melting point different from that defined as the standard in the Periodic Table, for example.
Learn more about Fusion.
| Substance | Formula | Tf/K |
Tf/°C |
|---|---|---|---|
| Ethanol | C2H5OH | 161,2 | -112,0 |
| Water | H2O | 273,1 | 0,0 |
| Benzene | C6H6 | 278,6 | 5,5 |
| Phenol | C6H5OH | 313,8 | 40,6 |
| naphthalene | C10H8 | 353,4 | 80,2 |
| Sodium | At | 370,8 | 97,7 |
| Lead | Pb | 600,1 | 327,0 |
| Iron | Faith | 1808,1 | 1535,0 |
Tf/°C = Melting temperature in Celsius
Tf/K = Melting temperature in Kelvin.
