Question

To make water boil at 75°C instead of 100°C, you would have to:

A. Add more heat
B. Increase air pressure
C. Decrease the volume of water you are boiling
D. Heat the water at a higher altitude

Answer 1

To make water boil at 75°C, you would need to heat the water at a higher altitude where the atmospheric pressure is sufficiently lower than at sea level.

Step-by-step explanation:

To make water boil at 75°C instead of 100°C, you would have to heat the water at a higher altitude. Boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid. The boiling point of water is 100°C at sea level, where the atmospheric pressure is standard (1 atm). However, at higher altitudes, the atmospheric pressure is lower, which means water will boil at a lower temperature. For example, in Denver, Colorado at 1600 m above sea level, the atmospheric pressure is about 640 mm Hg and water boils at about 95°C. Therefore, if one were to go even higher than this, it's conceivable to reach conditions where the atmospheric pressure is low enough to make water boil at 75°C.