
#1
Apr1113, 08:07 AM

P: 1

Hello, new to these forums
I'm trying to complete a basic thermodynamics problem, calculating the thermodynamic temperature of a gas immersed in water at triple point. The problem begins with a table of pressures at varying temperatures of a gas under pressure P, and pressure P(tp)  triple point pressure. Now, I know the following equation; T=LIM_{PTP→0}P/P_{TP} * 273.16 So I have calculated the average value of P/P_{TP} as 1.53555 But I also have access to a solution to this problem, and in the solution an extra step is also taken: I don't understand the source of the 2.5 * avg change between P and P(tp). Where has this come from? Why is it necessary? Thanks 



#2
Apr1113, 01:50 PM

P: 861

I don't understand either, but rather than trying to do so, I've used a more straightforward method. I evaluated P/P_{tp} to 5 decimal places for each of the five pairs of readings. It was then clear that the ratio increased by almost the same increment for each 250 mmHg decrement in P_{tp}. Hence naïve extrapolation of P/P_{tp} to zero pressure is very straightforward.



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