The freezing temperature of an alcoholic beverage depends on its alcohol proof. Rum is available in several different proofs, so it freezes at several different temperatures.
Rum typically has an alcohol proof of 80, which means it contains 40 percent alcohol. Captain Morgan manufactures a 100-proof spiced rum, which has an alcohol content of 50 percent. Liquor with an alcohol proof of 84 usually freezes at -30 F, while liquor with a proof of 24 freezes at 20 F. The higher the alcohol proof, the lower the freezing temperature of the liquor. This means that 100-proof rum has a lower freezing point than 80-proof varieties.