1. The problem statement, all variables and given/known data Expose the error: When sodium is placed in water, a violent reaction always occurs; therefore sodium and water can never be at the same temperature. 2. Relevant equations Thermal equilibrium and temperature. Zeroth law. Isotherms. 3. The attempt at a solution My Answer: The error is that sodium and water CAN be at the same temperature. The system will reach a thermal equilibrium.