Explain why putting salt on ice that forms on sidewalks and roadways to melt the ice and resist refreezing?

Thanks for the question!

When adding salt to roads and walkways, the salt acts to change the freezing temperature of the snow/water on the pavement. Isn't that neat! The freezing temperature lowers, and prevents the water from being able to freeze.

The actual reason that the application of salt causes ice to melt is that a solution of water and dissolved salt has a lower freezing point than pure water. When added to ice, salt first dissolves in the film of liquid water that is always present on the surface, thereby lowering its freezing point below the ices temperature.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.