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12) But is that right to assume 1 mole??? Should we ever assume? My tank was fil

ID: 103476 • Letter: 1

Question

12) But is that right to assume 1 mole??? Should we ever assume? My tank was filled with a mixture of oxygen and nitrogen at a ratio of 21%2 to 78 % N2. The total pressure on the tank gauge reads 15 at on my 25 L tank at the surface. a) (4 pts) What is the partial pressure of oxygen at the filling of the tank? Show work. bY4 pts) Now, calculate the number of moles of oxygen in my tank(at the surface) from this information? Show work. I have reached the surface, but too quickly, so I had to use the dry decompression chamber.

Explanation / Answer

a.

partial pressure of OXygen is that of "air"

therefore

mol fraction of O2 = 0.21

Ptotal = 15 atm

then

P-O2 = x-O2 * PTotal = 0.21*15 = 3.15 atm

b.

PV = nRT

assume T = 25°C = 298K

n = PV/(RT) = 3.15*25/(0.082*298) = 3.222 moles of O2