Molecular Weight of an Unknown Volatile Liquid

A substance, whether solid, liquid, or gas, has a number of characteristic properties that either alone or in combination can be determined experimentally in order to identify the substance. One characteristic property is the molecular weight which is numerically equal to the mass in grams of one mole or of the Avogadro number of molecules of the substance. 

For a volatile liquid the molecular weight determination can be made on the vapor. The pressure, P, volume, V, number of moles, n, and temperature, T, of an ideal gas are related by 

you can calculate the molecular weight of a liquid s vapor if the vapor behaves ideally and if the mass, temperature, pressure, and volume of the vapor are measured experimentally. 

and Purcell, K. F., Chemistry and Chemical Reactivity. Saunders College Publishing, Philadelphia, 1987, sections 2.10, 6.1, 6.3, and 11.3. 

Masterton, W. L., Slowinski, E. J., and Stanitski, C. L., Chemical Principles. 6th ed., Saunders College Publishing, Philadelphia, 1985, sections 2.5 and 6.2. 

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