All temperatures below are in Celsius.
Freezing points
Melting points of materials that are liquid or gas at room temperature are often thought of as freezing points.
-259 : Hydrogen
-219 : Oxygen
-210 : Nitrogen : curiously, oxygen and nitrogen flip when it comes to boiling points (-183 versus -196 respectively), or oxygen's liquid range completely covers nitrogen's.
-188 : Propane
-183 : Ethane
-182.5 : Methane : The above 3 are in a surprising order.
-159 : Isobutane, Methylpropane, i-Butane
-138 : Butane, n-Butane : unbranched.
-114 : Ethanol
-100 : Ammonia solution, Ammonia in water, Ammonium hydroxide, NH3(aq) : eutectic. The freezing point as the concentration of ammonia in water varies is complicated with 3 eutectic points. Why?
-98 : Methanol
-95 : Acetone
-91 : Cyclobutane
-89 : Isopropyl alcohol
-78.5 : Carbon dioxide, Dry ice : sublimates. Is the sublimation temperature of dry ice closer to -79 or -78?
-78 : Ammonia
-39 : Mercury
-21 : Brine, NaCl Brine, Sodium Choride in water : eutectic
-16.5 : Neopentane, Dimethylpropane
-13 : NaK, Sodium-Potassium alloy : eutectic
0 : Water, Ice
11 : Gallium-Indium-Tin : eutectic. Wikipedia notes a melting point controversy with Galinstan. Perhaps it can be supercooled to -19.
17 : Acetic acid : pure, glacial, anhydrous.
Melting points
30 : Gallium
37 - 68 : Paraffin wax
113 : Sulfur
232 : Tin
271 : Bismuth
327 : Lead
420 : Zinc
525 - 1000 : Red hot glow. Lower end is Draper point.
660 : Aluminum
770 : Potassium chloride
801 : Salt, Sodium chloride
962 : Silver
1064 : Gold
1083 : Copper
1400 to 1665 : Glass : depends on composition. Upper number is the softening point of silica glass (a.k.a. fused quartz), whose melting point is higher, probably the same as one of the quartz crystal structures.
1410 : Silicon
1453 : Nickel
1535 : Iron
1597 : Magnetite, Fe3O4, Iron(II,III) oxide, FeO . Fe2O3
1670 : Quartz, Silica, Silicon dioxide : tridymite crystal structure
1713 : Quartz, Silica, Silicon dioxide : crisobalite crystal structure
Also, when the temperature exceeded 573 C, quartz crystal structure changed from alpha to one of the beta structures.
1772 : Platinum
2072 : Sapphire, Ruby, Corundum, Alumina, Al2O3, Aluminum oxide
2613 : Calcium oxide : product of the thermal decomposition of calcium carbonate
3410 : Tungsten
3500 or 3642 : Carbon, Graphite : sublimates. The latter temperature is from Wikipedia.
Thermal decomposition
Many materials do not melt, but instead thermally decompose. Elements cannot thermally decompose.
171 - 186 : Sucrose, Sugar : thermal decomposition to caramel
825 : Calcium carbonate : thermal decomposition to calcium oxide and carbon dioxide
1200 - 1300 : Hematite, Fe2O3, Iron(III) oxide, Ferric oxide, Rust : decomposes to Fe3O4 and O2, and also FeO. Temperature range according to "Thermal Decomposition Behaviour of Fine Iron Ore Particles". 1565 is the melting temperature.
1539 - 1565 : Hematite, Fe2O3, Iron(III) oxide, Ferric oxide, Rust : Temperature range according to Wikipedia.
Element data from https://www.lenntech.com/periodic-chart-elements/melting-point.htm unless othewise noted (carbon).
I'm a little suspicious of the many temperatures ending in "3", having 3 in the one's place. They may have been converted from a Kelvin temperature precise only to 10 degrees, but the 3 at the end in Celsius then incorrectly suggests a precision of 1 degree.
I didn't try too hard to find reliable sources. Many values were copied from Wikipedia.
What commonly available substance, liquid at room temperature, has the lowest freezing point? Ethanol? Though pure ethanol is hard to obtain.
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