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Here is the problem:

moles = 0.10 of O_2

T(initial) = 150 C = 423 K

P(initial) = 3.0 atm = 303.9 KPa

The gas expands adiabatically until the pressure is halved, find the final volume and final pressure

Since the pressure is halved, we know that

P(final) = 1.5 atm = 151.95 KPa

I need the initial volume, so I used the ideal gas equation, PV = nRT

using the initial conditions with P in pascals, n in mols, T in kelvin, and R as 8.31 J/mol*K

So I get a V(initial) = 1.156 x 10^(-3) m^3

Then I need the final volume, and since this is adiabatic,

Pi(Vi)^(gamma)=Pf(Vf)^(gamma)

Since O_2 is diatomic and we assume ideal conditions, gamma = 1.4

So using the above equation, I find

V(final) = 1.37 x 10^(-5) m^3 = answer to part a

I don't know if this is right or wrong

Then for part b, I used the idea gas equaion again, PV=nRT

Using the final volume, final pressure, same n and same R, I get

T = 2.50 K

Obviously this is extremely COLD!! I don't think it makes sense that the temperature would drop from 423 K to 2.5 K....where did I go wrong?