Question

The atomic mass of iodine is `127 g//mol`. A standing wave in iodine vapour at `400 k` has nodes that are `6:77 cm` apart when the frequency is `1000 H_(Z)`. At this temperature, is iodine vapour monatomic or daiatomic.

Answer 1

`:. nu = f lambda = (1000) (2 xx 6.77 xx 10^(-2))`
`= 135.4 m//s = sqrt ((gamma RT)/(M))`
`:.gamma = (135.4)^(2) ((M)/(RT))`
`= ((135.4)^(2) (0.127))/(8.31 xx 400)`
`= 0.7`
Since, `gamma lt 1`
So, we will have to subsitute,
`M = 2 xx 0.127`
The `gamma` comes out to be `1.4` which is the `gamma` of a diatomic gas.