A system of physical chemistry - Index of

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A system of physical chemistry - Index of

ATOMIC HEATS OF SOLIDS 59

Tf we now regard the atomic volume V as proportional to the cube

of the mean distance apart of the atoms (which distance is identical with

r^ on Lindemann's assumption), we can write— "

IS

The proportionality factor obtained by comparison with experiment

2 'So X lo^^, and hence Lindemann's formula is—

2 "So X I

wV2/3

It is thus possible to calculate V from measurements of melting

temperature, molecular weight of the atoms, and the atomic volume.

This is an extremely convenient method, but has the disadvantage of

not giving v very accurately. It appears, however, to be somewhat

more accurate than Einstein's method (Method 2). The following

table is given by Nernst and Lindemann (Z. Elektrochem., 17, 822,

191 1). The observed values of v are those given by a formula of Nernst

and Lindemann which is a modification of Einstein's expression for

atomic heat, which at the same time represents experimental values

more closely. We shall discuss this expression later, but in the meantime

it may be taken as giving the values of v from atomic heat measurements.

Lindemann's Formula for " V ".

Substance.

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