Discussion Forum



1)

X and Y  are two volatile liquids with molar weights of 10 gmol-1 and 40 g mol-1 respectively, two cotton plugs, one soaked in X and the other soaked in Y, are simultaneously placed at the ends of a tube of length L=24 cm, as shown in the figure.

 The tube is filled with an inert gas at 1 atm pressure and a temperature of 300K. Vapours of X and Y react to form a product which is first observed at a distance d cm from the plug soaked in X. Take  X and Y to have equal molecular diameters and assume ideal behaviour for the inert gas and the two vapours.

2732021838_vapour.PNG

The experimental value of d is found to be smaller than the estimate obtained using Graham's law. This due to


A) larger mean free path for X as a compared of that of Y

B) larger mean free path for Y as compared to that of X

C) increased collision frequency of Y with the inert gas compared to that of X axis with the inert gas

D) increased collision frequency of X with the inert gas compared to that of Y axis with the inert gas

Answer:

Option D

Explanation:

Collision frequency  is the measurement of number of molecular collision taking place per second  per unit volume of a gas

 As the collision frequency increases, molecular size increases and hence covered distance decreases than the expected value.

 Since speed is higher for x so it produces more collisions per second. i.e, more collision frequency and hence

 covers lesser distance than that predicted by Graham's law  

 Hence (d) is the correct choice