What is the boiling point of water at 085 bar 1 bar and 2 ba

What is the boiling point of water at 0.85 bar, 1 bar, and 2 bar respectively? Interpret the results to elaborate why it takes a) longer to cook meat and potatoes on mountain tops b) shorter time to cook and potatoes in a pressure cooker. A silicon chip measuring 5 mm on a side and 1 mm in thickness is embedded in a ceramic substrate. At steady state, the chip has an electric power input of 0.250 W. The top surface of the chip is exposed to a coolar whose temperature is 20 decree C. If the surface temperature of the chip must be no greater than 60 degree C, what is the corresponding range of values for the heat transfer coefficient for convection between chip and the coolant assuming all other quantities remain unchanged?

Solution

1 (a),

Answer:

Boiling point of water at 0.85 bar is 95.207°C

Boiling point of water at 1.0 bar is 99.646°C

Boiling point of water at 2.0 bar is 118.577°C

(a) Why it takes longer to cook meat and potatos on mountain top:

The temperature and the pressure are connected, so on low altitudes, like on the sea level the pressure is approximately around 1 bar, so the water boils faster.

At higher altitudes, air pressure is lower. So it takes less energy to bring water to the boiling point. Less energy means less heat, which means water will boil at a lower temperature at a higher altitude.

This means vapor pressure on water decreases as elevation increases. This results to easier escape of water molecules because the vapor pressure pushing them down is decreased.

So when we cook meat or potato in a water on top of a mountain, the water has already evaporated leaving from meat or potato partially cook or worse still raw. This makes cooking with water very hard and will take longer time.

(b) Why it takes shorter time to cook meat and potatos in a pressure cooker:

Similarly, the pressure cooker works on the principle that when the pressure inside the cooker is increased by preventing the escape of steam, a higher temperature produced which cooks the meat and potato faster.