Choose any two temperatures and corresponding vapor pressures in the table given
ID: 800519 • Letter: C
Question
Choose any two temperatures and corresponding vapor pressures in the table given, and use those values to calculate Delta H vap for mercury (in kJ / mol).
I have no idea how to do this problem. Please show step by step with correct answers so I can try to understand.
Thank you!!!
T (K ) Pvap (mm Hg ) 500 39.3 520 68.5 540 114.4 560 191.6 580 286.4 600 432.3 Choose any two temperatures and corresponding vapor pressures in the table given, and use those values to calculate Delta H vap for mercury (in kJ / mol). I have no idea how to do this problem. Please show step by step with correct answers so I can try to understand.Explanation / Answer
Clausius-Claperyon equation:
ln(P2/P1) = (-DHvap/R) x (1/T2 - 1/T1)
Molar gas constant R = 8.314 J/mol.K
Choosing a pair of (P,T) values from table (you can choose any pair but here we have used the values at 500 K and 600 K):
P1 = 39.3 torr, T1 = 500 K
P2 = 432.3 torr, T2 = 600 K
Substituting values into equation:
ln(432.3/39.3) = (-DHvap/8.314) x (1/600 - 1/500)
Heat of vaporization = DHvap = 5.98 x 10^4 J/mol = 59.8 kJ/mol