Gaseous and Liquid State (Physical Chemistry–I) — DU B.Sc (hons) Chemistry Previous Year Question Papers

State (Physical Chemistry 1) (c) The coefficient of viscosity of n-heptane is 0.0001328 Poise at 298 K. Calculate the molecular diameter of this gas. Molecular mass of n-heptane is 100 g mol!. (5) 3. (a) Calculate the pressure of a barometer on an aeroplane which is at an altitude of 10 km. Assume the pressure to be 101.325 kPa at sea level and the mean temperature 243 K. Use the average molar mass of the air (80% N2 and 20% O,). (b) The mean free path of the molecule of a certain gas at 300 K is 2.6 × 10-' m. The collision diameter of the molecule is 0.26 nm. Calculate pressure of the gas and the number of molecules per unit volume of the gas. (5) (c) Using van der Waals equation, define and calculate the critical constants. Also explain with PV diagram the continuity of state. 4. (a) Write an expression of Maxwell Distribution of speeds. Convert this expression into Energy Distribution. Show the plots of these distribution as variation of speed and energy. (b) Write the cubic form of van der Waals equation and compare with the given equation for the calculation of 2nd Virial coefficient. (c) At 20°C, pure water with an absolute viscosity of 1.002 × 10-3 Nm-° s requires 102.2 s to flow through the capillary of an Ostwald viscometer. At 20°C, toluene requires 68.9 s. If the densities of water and toluene be 0.998 and 0.866 g cm-3, respectively, calculate the viscosity of toluene.