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32
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273.15
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32
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273.15
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The Melting Point Calculator provides the melting points of common elements, metals, and chemical compounds at standard atmospheric pressure. Select a substance from the comprehensive dropdown list to instantly view its melting temperature in Celsius, Fahrenheit, and Kelvin. This reference tool is essential for metallurgists, chemists, materials scientists, and students studying phase transitions.
The melting point (or freezing point) is the temperature at which a substance transitions from solid to liquid at a given pressure. It is one of the most important physical properties for characterizing and identifying materials, and is crucial for applications ranging from metal casting to pharmaceutical formulation.
The melting point is a thermodynamic equilibrium property where the solid and liquid phases of a pure substance coexist. At this temperature, the Gibbs free energy of the solid equals that of the liquid:
$$G_{solid}(T_m, P) = G_{liquid}(T_m, P)$$
Temperature conversions between scales follow the standard formulas:
$$T_F = T_C \times \frac{9}{5} + 32$$
$$T_K = T_C + 273.15$$
The melting point of a substance is determined by the strength of its interatomic or intermolecular forces. Metals with strong metallic bonds (tungsten, 3422°C) and covalent network solids (diamond, 3550°C) have very high melting points. Ionic compounds (NaCl, 801°C) have moderate to high melting points due to strong electrostatic forces. Molecular substances with only weak van der Waals forces (benzene, 5.5°C) have low melting points. Crystal structure symmetry also plays a role — more symmetrical molecules tend to pack better and have higher melting points.
The melting point values represent measurements at standard atmospheric pressure (1 atm). A higher melting point generally indicates stronger bonding forces holding the solid together. For metals, the melting point is critical for determining casting temperatures, welding parameters, and operational temperature limits. For molecular compounds, it helps in purification (recrystallization) and identification. Impurities typically lower the melting point and broaden the melting range.
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Gold melts at 1064°C (1947°F). This relatively moderate melting point for a metal made gold one of the first metals to be smelted and cast by ancient civilizations.
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Mercury is the only metal that is liquid at room temperature, with a melting point of -38.83°C. This unique property made it valuable in thermometers and barometers for centuries.
The melting point is the temperature at which a substance transitions from the solid phase to the liquid phase at standard pressure. At this temperature, both solid and liquid phases coexist in thermodynamic equilibrium. For pure substances, this occurs at a sharp, well-defined temperature.
For a pure substance, the melting point and freezing point are the same temperature. The difference is the direction of the transition: melting goes from solid to liquid (endothermic), while freezing goes from liquid to solid (exothermic). Some substances can be supercooled below their freezing point without solidifying.
Tungsten has the highest melting point of any pure metal (3422°C) due to its extremely strong metallic bonds. Tungsten atoms have half-filled d-orbitals that form very strong directional bonds. This makes tungsten ideal for applications like incandescent light bulb filaments and welding electrodes.
Mercury's low melting point (-38.83°C) is caused by relativistic effects on its electrons. The 6s electrons travel at speeds approaching the speed of light, causing them to contract closer to the nucleus and become less available for metallic bonding, resulting in unusually weak interatomic forces.
Molecules with higher symmetry tend to pack more efficiently in the crystal lattice, requiring more energy to disrupt and resulting in higher melting points. For example, para-dichlorobenzene (mp 53°C) melts much higher than the less symmetrical ortho-isomer (mp -17°C) despite having the same molecular formula.
Ionic compound melting points depend on the lattice energy, which increases with higher ion charges and smaller ionic radii. MgO (2852°C) melts much higher than NaCl (801°C) because Mg²⁺ and O²⁻ have higher charges than Na⁺ and Cl⁻.
For most substances, increasing pressure raises the melting point because the solid phase is denser than the liquid. Water is a notable exception — its melting point decreases slightly under pressure because ice is less dense than liquid water. This allows ice skating, as pressure under the blade slightly lowers the melting point.
Tantalum hafnium carbide (Ta₄HfC₅) holds the record for the highest melting point of any known substance at approximately 4215°C (4488 K). Among elements, carbon (as diamond) sublimes at about 3550°C under standard pressure, and tungsten melts at 3422°C.
Common methods include differential scanning calorimetry (DSC), the capillary method (Thiele tube), hot-stage microscopy, and the falling-drop method. DSC is the most precise, measuring the heat flow during the phase transition to determine both the melting temperature and the enthalpy of fusion.
Impurities disrupt the regular crystal lattice structure of the solid, making it energetically easier to break apart. This is a manifestation of freezing point depression — the impurity acts as a solute. A sharp melting point indicates high purity, while a broad melting range suggests impurities.
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