DETERMINATION OF VAPOUR PRESSURE TAs Utsab Mukherjee (123020004) - PowerPoint PPT Presentation

TH 202 EBULLIOMETRIC DETERMINATION OF VAPOUR PRESSURE TA’s  Utsab Mukherjee (123020004)  Bharath Ravu (134024001)  Maanya Gaur(134024002) Staff: Nirmal Karangale

OBJECTIVES  T o determine saturation temperature of a liquid at a set pressure.  T o determine Antoine constants (A,B)  T o determine latent heat of vaporization.

THEORY  Boiling point : the temperature at which vapor pressure of the liquid becomes equal to the ambient pressure and liquid turns into vapor.  The dependence of vapor pressure of the liquid at a given temperature is given by Clausius-Clapeyron equation Δ H v : enthalpy of vaporization

Experimental set up

Sample Observations Correction factor = 63 mm Hg

Sample Observations 90 80 70 emperature(deg C) 60 50 40 30 T 20 10 0 0 10 20 30 40 50 60 Time(mins)

Questions 1. Using temperature measurements how do you know whether the system has reached equilibrium or not? 2. How to make sure from the drop rate count that the liquid is not in a super-heated or sub- cooled state? (do this only at 760 mm Hg)? 3. Determine the correlation constants in the vapour pressure equation. Estimate latent heat of vaporization and compare to literature.

Questions 4. Is the set pressure equal to total pressure or vapour pressure of the liquid? Will this affect calculated latent heat of vaporization? 5. How can this experiment and the calculation methods be improved?

Safety measurements  Don’t increase the rheostat voltage excessively. It may lead to very fast generation vapor causing poor condensation. Finally vapor can deposit as liquid in the manometer.  Don’t go below vacuum pressure of 250 mm Hg. It may lead to the abovementioned problem.

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