Final answer:
Water at 100°C and a pressure of 2 atm would be in the liquid phase. The boiling point of water increases with pressure, so at 2 atm, it is still below the required vapor pressure to become gas.
Step-by-step explanation:
In determining whether water would be a solid, liquid, or gas at a temperature of 100°C and a pressure of 2 atm, we refer to the phase diagram of water. At 100°C, which is typically the boiling point of water at 1 atm, an increase in pressure to 2 atm would result in a phase where water remains liquid because the boiling point increases with higher pressure. This is due to the boiling point being the temperature at which the vapor pressure of the liquid equals the external pressure. At 2 atm and 100°C, water is not yet at the vapor pressure needed to transition to gas, so it remains in the liquid phase. In general, phase diagrams show that as pressure increases, the temperature at which water changes from liquid to gas (boiling point) also increases. Therefore, if the temperature is held at 100°C and the pressure is raised above 1 atm to 2 atm, water does not enter the gaseous state but remains liquid.