Question

tions ecular nsity. dns o the Hg le? utial pressures mm Hg 23) which of the following zares has the highest rate of effusion? A. NO2 B.Cl c . Ca Ho D. F E. O 24) The Molar Moss (M. w) of 6.5 g gas at 20c and 720 fors that dccupies 2000 mL Volume?

Answer 1

(1) The rate of effusion is indirectly proportional to the molar mass of the gas.

So in the given example, C₂H₆ (M.W~30 g/mol) has the highest rate.

(2) According to ideal gas law,

PV=(W/M) RT ------------(1)

Given, P=720 torr=720*0.00131579 atm=0.9474 atm.

V=2000 mL=2 L.

R=0.082057 L atm mol^-1K^-1

W=6.5 g

T=20⁰ C=20+273 K=293 K.

From Eq. (1), one gets

Molar mass M=WRT/ PV=(6.5 g*0.082057 L atm mol^-1K^-1*293 K)/(0.9474 atm*2 L)~82.5 g/mol.