Question

6. An ideal monatomic gas initially at 26.85 K and 3.250 bar is added to a 1.750 L vessel. Assuming that the system consists of the ideal gas alone, calculate the values of Vf, Tf, Pf, w, q, ΔU, and ΔH for each of the following processes. Construct a table for each part listing the initial and final value of V, T, and P and the value of w, q, ΔU, and ΔH.

Answer 1

Confusion about the question.................

How the process is being carried out ?? This is the case of free expansion of ideal gas....

PV = RT

V = RT/P = (1 mol) (8.314 x 10^-2 L bar K^-1 mol^-1 x 26.85 K)/3.25 bar = 0.69 L (round off)

Pf = RT/Vf = (1 mol) (8.314 x 10^-2 L bar K^-1 mol^-1 x 26.85 K)/1.75 L = 1.28 bar

This is a case of free expansion of ideal gas against zero pressure. This is usually carried out at constant temperature (isothermally). = 0, Tf=Ti

So, w = 0, Q= = 0,

= + = = 0 [ since no change in external pressure, no work involved]

= 0

Vf Pf Tf w Q   

1.75L 1.28 bar 26.85K 0 0 0 0

For an ideal gas U and H are function of temperature only