Question

Please answer and explain reasoning for each part

1. When food is cooked in a pressure cooker,
   1. why is it very important to cool the container with cold water before attempting to remove the lid? Explain your reasoning.
   2. b. would you dare to place your bare hand about 1 foot above the steam coming out of the cooker’s vent pipe? Why, or why not?
   3. c. would you dare to place your bare hand about 1 inch above the steam coming out of the cooker’s vent pipe? Why, or why not?

Answer 1

(a)

In a pressure cooker the pressure can be very high (1-2 atm) when the food is being cooked. The pressure rises due to change in temperature which in turn is the result of the heat provided by the gas stove. Due to high steam pressure relative to the atmospheric pressure, the lid gets tightened and it gets harder to remove the lid. To reduce the pressure, the temperature of the pressure cooker is lowered with cold water.

(b)

The steam inside the pressure cooker is at high temperature (100°C -125°C), which is capable of burning our skin. Steam coming out of the cooker's vent pipe is at high temperature. But while traveling a distance of 1foot the temperature is much lowered due to interaction of steam with the air through which the steam travelled. Thus, 1 foot becomes a safe distance to place you bare hands above the cooker's vent pipe.

(c)

1inch is not a safe distance to place your bare hand above the cooker's vent pipe as it can cause severe burns. The steam did not interact with enough surrounding air to lower its temperature to safer level.