At what temperature does pure water boil at standard atmospheric pressure (1 atm)?

• A. 0 °C
• B. 50 °C
• C. 212 °C
• D. 100 °C

Answer: (D)

Verified step by step guidance

1. Understand that the boiling point of a liquid is the temperature at which its vapor pressure equals the external pressure. For water at standard atmospheric pressure (1 atm), this is the temperature where water changes from liquid to gas.
2. Recall that standard atmospheric pressure is defined as 1 atm, which is the pressure at sea level.
3. Know that the normal boiling point of pure water is the temperature at which its vapor pressure is exactly 1 atm.
4. Use standard reference data or the phase diagram of water, which shows that at 1 atm pressure, pure water boils at 100 °C.
5. Therefore, the temperature at which pure water boils at 1 atm is 100 °C.