286.9 J/kg/K is the ideal gas law constant for air, the molecular of air is 29 T

Question

286.9 J/kg/K is the ideal gas law constant for air, the molecular of air is 29 The specific heat of water is 4.19 kJ/kg/K. Find the boiling point of water at 5,000 meters elevation to the nearest 3 degrees (i e, don't bother to interpolate). Explain your logic. Specifically, a) what is the pressure at this point? b) describe in words how you will go about finding the boiling point (i.e., what's your logic): c) find the approximate boiling point (a range between two table numbers is OK, don't bother to interpolate) Variation of the standard atmospheric pressure and boiling (saturation) temper of water with altitude

Explanation / Answer

1.(9) Boiling point of water at sea-level is 212 oF. Boiling point of water decreases by 0.933 oF for every 500 feet in height.

So, for 5000 feet in height, boiling point decreases by (0.933 * 10) oF = 9.33 oF

Therefore, boiling point of water at 5000 feet = 212 oF - 9.33 oF

= 202.67 oF = 94.82 oC

(a) At 5000 feet elevation, the atmospheric pressure is 54.05 kPa as given in the table.

(b) To find the boiling point of water at high elevations, we can take a pressure cooker, a thermometer and some water with us.

At each elevation, we will boil some water inside the pressure cooker. Once the water starts to boil, we will measure the boiling point using the thermometer (which is already inserted into the pressure cooker)

In this way, we can measure the boiling point of water at each elevation.

(c) Boiling point of water at 0 feet (at sea-level) = 100 oC

Boiling point of water at 20000 feet = 79.9 oC

Therefore, average boiling point between 0 feet and 20000 feet = 89.95 oC

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