Question

An oxygen cylinder in a cell plate is filled to (1800) psi G at (70°F). The pilot takes off to a Clemson altitude where the temperature is (-35°F). If the pilot's use of oxygen reduces the pressure by (400) psi G per hour, what will the pressure gauge read after (2) hours of flight?

(A) (1000) psi G
(B) (1200) psi G
(C) (1400) psi G
(D) (1600) psi G

Answer 1

To solve this problem, we use the ideal gas law to find the final pressure after 2 hours of flight. The answer is (C) (1400) psi G.

Step-by-step explanation:

To solve this problem, we need to use the ideal gas law, which states that PV = nRT. Where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. In this case, we have the initial pressure, volume, and temperature, and we need to find the final pressure after 2 hours of flight.

First, we convert the initial pressure from psi G to absolute pressure by adding the atmospheric pressure. So, the initial absolute pressure is (1800 + 14.7) psi.

Next, we convert the initial temperature from Fahrenheit to Kelvin. The conversion formula is: K = (°F - 32) * 5/9 + 273.15. So, the initial temperature is (70 - 32) * 5/9 + 273.15 K.

Using the ideal gas law, we can find the initial number of moles of oxygen by rearranging the equation to n = PV / RT. Substitute the initial values for P, V, and T to find the initial number of moles.

Now, we can calculate the final pressure after 2 hours of flight. Since the pressure reduces by 400 psi G per hour, the final absolute pressure is the initial absolute pressure minus (2 * 400) psi.

To convert the final absolute pressure back to psi G, subtract the atmospheric pressure from the final absolute pressure.

The answer is (C) (1400) psi G.