On Jun 29, 2011 6:03 PM, "Joshua Cude" <[email protected]> wrote: > > You yourself argued at length that the temperature > is not above the boiling point, as evidenced by its > perfectly flat nature. You argued it was because only > liquid water is heated directly. If the steam is dry > and above the bp, then the steam must be heated > directly, and then there is no explanation for its > perfect flatness. > Good try but you forgot the surface tension. When you boil water in the kettle then you will get bubbles. Therefore steam can be hotter than actual boiling point. If you reduce the surface tension or make fine mist like in your setup, then steam temperature is closer to boiling point. Of course there is a limit how big steam bubles can get and how hot steam can go through liquid water in bubbles. Therefore steam is heated to about 101.0±1.0°C, if boiling point is calbrated to be 99.7±0.1°C. This of course depends heat difference between heating element and boiling water.
Daniel calculated the actual boiling point. But thermometers absolute accuracy is ±0.4°C, although it's relative accuracy is ±0.1°C. Therefore thermometer must be calibrated and actual boiling point must be measured. In absolute sense boiling point was 99.7±0.4°C, but we do not need this figure because we measure relative temperatures where accuracy is ±0.1°C. —Jouni
