At standard conditions, what is the boiling point of water?

At standard conditions, what is the boiling point of water?

• A. 90 degrees Celsius
• B. 100 degrees Celsius
• C. 120 degrees Celsius
• D. 80 degrees Celsius

Answer: (B)

The boiling point is the temperature at which a liquid’s vapor pressure equals the surrounding pressure. At standard conditions, the surrounding pressure is 1 atmosphere (about 101.3 kPa). Under that pressure, water reaches a vapor pressure of 1 atm at 100 degrees Celsius, so it begins to boil. Thus, at standard conditions, water boils at 100 degrees Celsius. The other temperatures would occur at different pressures, not at standard atmospheric pressure.

The boiling point is the temperature at which a liquid’s vapor pressure equals the surrounding pressure. At standard conditions, the surrounding pressure is 1 atmosphere (about 101.3 kPa). Under that pressure, water reaches a vapor pressure of 1 atm at 100 degrees Celsius, so it begins to boil. Thus, at standard conditions, water boils at 100 degrees Celsius. The other temperatures would occur at different pressures, not at standard atmospheric pressure.