Why would an iron nail not rust in water and a chemical to absorb water vapur?

An iron nail would not rust in water if it is kept in a chemical that absorbs water vapor, as rusting requires both moisture and oxygen. By removing water vapor from the environment, the conditions necessary for the oxidation of iron (which leads to rust formation) are eliminated. Additionally, without sufficient oxygen, the electrochemical reactions that cause rusting cannot occur. Therefore, the nail remains protected from corrosion.