The electric susceptibility of water vapour is strongly dependent on temperature:
`{:("Temperature t,", ""^(@)C, 120,150,180,210),("Pressure p,", mm Hg, 565,609,653,698):}`
Electric susceptibility `chi_(e) 4.00xx10^(-3),3.72xx10^(-3),3.49xx10^(-3)3.29xx10^(-3)`
Plot a graph and find the temperature dependence of the electric susceptibility. Calculate the dipole moment of a molecule of water.

Explanation

To plot the graph it is convenient to use new variables: `x=10^(3)//T` where T is the absolute temperature, and `y=10^(3)chi_(e)` where `chi_(e)` the electric susceptibility. The respective values are presented in Fig. 25.9, from which it may be seen that the Debye law is well satisfied in the experimental range (see 38.6). Because of this, let us use formula (38.26) to calculate the dipole moment of the water vapour molecule, and the gas equation to calculate the molecular concentration.
It is advisable to carry out the computations for all four experimental points and a verage the results.