Which of the following conditions will make water boil at a temperature of 100oC when the atmospheric pressure is 750mmHg?
Answer Details
Water boils when its vapor pressure equals the atmospheric pressure above it. The atmospheric pressure decreases with altitude. At sea level, the atmospheric pressure is about 760 mmHg, and pure water boils at 100°C. However, at high altitudes where the atmospheric pressure is lower than 760 mmHg, water boils at a lower temperature than 100°C. Therefore, to make water boil at a temperature of 100°C when the atmospheric pressure is 750 mmHg, the external pressure needs to be increased to match the vapor pressure of water at 100°C and 750 mmHg. Thus, the correct option is "increase the external pressure."