Answer :
Final answer:
Water boils at 100°C at atmospheric pressure, but the boiling point can vary with changes in pressure. At lower pressures such as 12 kPa, water can boil at just 50°C.
Explanation:
Water typically boils at 100°C at a pressure of 1.00 atm because at this temperature, the vapor pressure of water equals atmospheric pressure, allowing it to form bubbles and evaporate without limit. However, the boiling point of water changes with pressure. If the pressure is reduced, water can boil at a lower temperature. For instance, at higher altitudes, where the pressure is lower, water boils at a temperature below 100°C. The question asks which pressure will cause water to boil at 50°C. According to phase diagrams and vapor pressure principles, the answer is 12 kPa; at this reduced pressure, water's boiling point decreases significantly.
