How can you determine the molecular weight of a material experimentally?

Answer 1

You can determine the Molecular Weight of a Volatile Liquid by the Dumas Method. It uses the ideal gas law. In this method we have to confine a sample of gas in a container of known volume, making sure when we do this that the sample is exactly at atmospheric pressure. The temperature and the mass of the gas sample have to be measured, along with the atmospheric pressure. Because liquids are much easier to handle than gases, a volatile liquid is usually used as the source of the gas. The liquid must have a boiling point substantially above room temperature and below the boiling point of water in order for this method to work well.
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Answer 2

There are lots of ways. As Fadia pointed out, the Dumas method is one. There are also methods based on colligative properties, like melting point depression and osmotic pressure, and titrations (if the compound is an acid or a base, for example). By far the most common technique used at present, however, is mass spectrometry, which is capable of "weighing" individual atoms and molecules (including proteins and nucleic acids) to extremely high accuracy.

Answer 3

You can determine the molecular weight of a solid organic compound by freezing point depression. You mix a small amount of the compound with a larger amount of camphor, which has a large molal constant of freezing point depression, and take the melting point.

Answer 4

your question lacks sufficient info. Molecular weight of what? gas? solids? beverages? often talking, the least complicated(?) and quickest thank you to confirm molar weight may be by potential of mass spectroscopy or mass spectrometer.