At what temperature does water freeze at standard conditions?

At what temperature does water freeze at standard conditions?

• A. -10 degrees Celsius
• B. 0 degrees Celsius
• C. -5 degrees Celsius
• D. 25 degrees Celsius

Answer: (B)

The temperature at which water changes from liquid to solid under standard atmospheric pressure is 0 degrees Celsius. At 1 atmosphere, pure water reaches a balance point between the liquid and solid phases right at 0°C, so that is the freezing point. If you lower the temperature below 0°C, water would already be ice; if you raise it above 0°C, ice would melt and water would be liquid. The other temperatures don’t fit because -5°C or -10°C are below the freezing point (water would be solid there), and 25°C is well above it (water would remain liquid).

The temperature at which water changes from liquid to solid under standard atmospheric pressure is 0 degrees Celsius. At 1 atmosphere, pure water reaches a balance point between the liquid and solid phases right at 0°C, so that is the freezing point. If you lower the temperature below 0°C, water would already be ice; if you raise it above 0°C, ice would melt and water would be liquid. The other temperatures don’t fit because -5°C or -10°C are below the freezing point (water would be solid there), and 25°C is well above it (water would remain liquid).