Solid iodine is added to a glass tube, which is evacuated to remove all other components, sealed and heated to 50°C. There are a few solid crystals in the bottom of the tube and a visible colored vapor filling the remainder of the tube. A second tube is prepared identically, but twice the amount of iodine is added. The second tube is evacuated of all other components, sealed and heated to 50°C. How are the two tubes different? Explain.