P/T is a constant at constant (tank) volume and amount (moles) of gas. T must be an absolute temperature. Either Kelvin or Rankine will work.
T1 = 92F = 552 R
T2 = 50F = 510 R
"R" is the absolute Rankine temperature. You get it by adding 460 to the Fahrenheit temperature.
P2/P1 = T2/T1 = 510/552 = 0.9239
P2 = 207 atm
A scuba diver takes a tank of air on a deep dive. The tank's volume is 10 L and it is completely filled with air at an absolute pressure of 224 atm at the start of the dive. The air temperature at the surface is 92 F and the diver ends up in deep water at 50 F. Assuming thermal equilibrium and neglecting air loss, determine the absolute internal pressure of the air when it is cold.
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