Question

Question 7

An atomic beam is designed to function with cadmium.  The source is an oven maintained at 380 K.  The oven has a small slit with dimensions of 1.0 cm x 1.0x10^-3 cm.  The vapour pressure of cadmium is 0.13 Pa.  What is the atomic current (number of atoms/second) in the beam of escaping particles?

Answer 1

ANSWER :

Given:

The dimension = 1 cm x 1cm x 10-3 cm = 10-3 cm3

The vapor pressure of cadmium = 0.13 Pa

The temperature, T = 380 K

The volume of slit, V = 1 cm * 1 cm * 10-3 cm

= 10-3 cm3

= 10-3 cm3 * (1m / 102 cm)3 * ( 1 cm / 10-1 m)3 * (1 L/1cm3)

V = 10-6 L

The moles of cadmium coming out, = RT / PV

= 0.08206 * 380 / [ 0.13 * (9.869 * 10-6 / 1 Pa) * (10-6 L)]

= 2.43 * 1013 mol

The no. of atoms = 2.43 * 1013 * (6.023 * 1023 / 1mol)

= 1.46 * 1037 atoms

So, if the slit release 1.46 * 1037 atoms per second, the the atomic current is 1.46 * 1037