Assuming standard pressure, at what temperature is there an equilibrium between water vapor and liquid water?
I don't understand your question. There is always an equilibrium between liquid water and vapor pressure in a closed system.
The temperature at which an equilibrium is established between water vapor and liquid water is known as the boiling point of water. It occurs when the vapor pressure of water becomes equal to the atmospheric pressure, typically at standard pressure (1 atmosphere or 101.325 kilopascals).
To find the equilibrium temperature, we can reference a phase diagram that shows the relationship between temperature and pressure for a substance.
For water, the phase diagram indicates that at standard pressure, the equilibrium between water vapor and liquid water occurs at 100 degrees Celsius, or 212 degrees Fahrenheit. This is commonly known as the boiling point of water at sea level.
Keep in mind that the boiling point of water can change depending on the pressure. For example, at higher altitudes where atmospheric pressure is lower, the boiling point of water decreases. Conversely, at higher pressures, such as in a pressure cooker, the boiling point of water increases.