By Liz Veloz | Updated Aug 30, 2022
Ice melts noticeably faster when placed in plain water compared to soda. The key difference lies in the presence of sodium (salt) in soda, which lowers the freezing point and requires more energy to break water’s hydrogen bonds.
Water molecules are linked by weak hydrogen bonds that continually break and reform. These bonds give water its unique fluidity and allow it to remain liquid from 32°F to 212°F. The movement of atoms becomes slower as temperatures drop, eventually leading to the solidification of ice.
Sodium ions in soda interfere with hydrogen bonding, reducing the number of free water molecules that can form a solid lattice. As a result, the melting point of ice in soda falls below 32°F, meaning ice takes longer to melt than in plain water.
In cold regions, salt is commonly spread on roads to keep ice from forming, keeping the surface liquid at temperatures that would otherwise freeze. The same principle explains why ice melts more slowly in soda: the salt keeps the solution below the usual freezing threshold.
