Condensation point at standard pressure
The condensation point of water in degrees Fahrenheit is 212 °F when the pressure is standard atmospheric pressure (\(1\,\text{atm}\)) and the substance is pure water. The same temperature is also described as the normal boiling point, because liquid–vapor equilibrium is shared by boiling and condensation.
Temperature conversion to degrees Fahrenheit
The Fahrenheit–Celsius relationship is:
\[ T_F = \frac{9}{5}\,T_C + 32. \]
Under \(1\,\text{atm}\), the condensation temperature for water is \(T_C = 100\,^\circ\text{C}\). Substitution gives:
\[ T_F = \frac{9}{5}\cdot 100 + 32 = 180 + 32 = 212\,^\circ\text{F}. \]
Physical meaning in general chemistry
Condensation converts water vapor to liquid water. At the condensation point, vapor and liquid coexist in equilibrium, so the net rate of condensation equals the net rate of evaporation. The equilibrium temperature depends on pressure because vapor pressure is a strong function of temperature.
Pressure dependence and common interpretations
The value \(212\,^\circ\text{F}\) corresponds specifically to \(1\,\text{atm}\). At lower external pressure (high altitude or vacuum), the condensation/boiling temperature is lower; at higher pressure (pressure cooker), it is higher. Dissolved solutes also shift the phase-change temperature by changing the chemical potential of the liquid, producing boiling-point elevation and freezing-point depression in solution chemistry.
Condensation point and dew point
“Condensation point” for pure water in a phase-equilibrium sense is the liquid–vapor transition temperature at a specified pressure. “Dew point” refers to condensation of water vapor from air and is controlled by the partial pressure of water vapor (humidity), not by total pressure alone. The dew point is commonly far below \(212\,^\circ\text{F}\) because atmospheric water vapor is typically well below saturation at \(100\,^\circ\text{C}\).
Reference temperatures for water
| Process | Temperature in °C (at 1 atm) | Temperature in °F | Phase equilibrium |
|---|---|---|---|
| Freezing / melting | \(0\,^\circ\text{C}\) | \(32\,^\circ\text{F}\) | Solid ⇌ liquid |
| Condensation / boiling | \(100\,^\circ\text{C}\) | \(212\,^\circ\text{F}\) | Liquid ⇌ vapor |