What is the temperature of steam? When steaming veggies in a covered pot?

Answer 1

In physical chemistry, and in engineering, steam refers to vaporized water. It is a pure, completely invisible gas (for mist see below). Pure steam (unmixed with air, but in equilibrium with water-liquid) has a temperature of around 100 degrees Celsius at standard atmospheric pressure, and occupies about 1,600 times the volume of liquid water (steam can of course be much hotter than the boiling point of water; such steam is usually called superheated steam). In the atmosphere, the partial pressure of water is much lower than 1 atm, therefore gaseous water can exist at temperatures much lower than 100 C (see water vapor and humidity).

Answer 2

The temperature of free steam at sea level is about 212F. A pressure cooker with a fastened lid and vent weight can raise the pressure and temperature. The normal pressure of the atmosphere at sea level is 14.7 pounds per square inch. If you calculate the weight of your cover (A = Pi R2 or Pi radius squared) and divide that into the weight of the cover (in pounds) the increased pressure and temperature should be nil (unless the cover is heavy cast iron?). Cooking in boiling water with a lid should force out all the air and cover the veggies with live steam at nearly 212F. The lid also prevents cooler air from entering the pot and wasting some of the heat from the burner. You are not trying to make hot air.

Answer 3

The temp at which water exerts a vapor pressure of 1 atm is 100 deg C. This is the normal boiling point. You can see water vapor "steaming" from hot water at a lower temperature, so your first question doesn't have an exact answer. The steam from a covered pot is probably at 100 degC, particularly if the water is boiling.

Answer 4

Aproximately 100 degrees Celsius depending upon the height of your place, the salinity of the water used and the leak tightness of the pot. The boiling point of water is modified by altitude, atmospheric pressure and the dissolved salt conents. If the lid is truly leak tight (like in a pressure cooker), altitude effects can be discounted.

If you are really interested, you can put a sensor inside and measure the temperature.