The Victor Meyer apparatus is the standard laboratory method for determining the

molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

of a volatile

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

. It was developed by

Viktor Meyer Viktor Meyer (8 September 18488 August 1897) was a German chemist and significant contributor to both organic and inorganic chemistry. He is best known for inventing an apparatus for determining vapour densities, the Viktor Meyer apparatus, and ...

, who spelled his name ''Victor'' in publications at the time of its development. In this method, a known mass of a volatile solid or liquid under examination is converted into its vapour form by heating in a Victor Meyer's tube. The vapour displaces its own volume of air. The volume of air displaced at experimental temperature and pressure is calculated. Then volume of air displaced at

standard temperature and pressure Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union o ...

is calculated. Using this, mass of air displaced at 2.24 × 10⁻² m³ of vapour at STP is calculated. This value represents the molecular mass of the substance. The apparatus consists of an inner Victor Meyer's tube, lower end of which is in form of a bulb. The upper end of tube has a side tube that leads to a trough filled with water. The Victor Meyer's tube is surrounded by an outer jacket. In the outer jacket, a liquid is placed, which boils at a temperature at least 30 K higher than the substance under examination. A small quantity of glass-wool or asbestos pad covers the lower end of the Victor Meyer's tube to prevent breakage, when a glass bottle containing the substance under examination is dropped to it Viktor Meyer vapor density apparatus prop 103abc

Viktor Meyer vapor density apparatus prop 103abc

Procedure

The liquid in the outer jacket is heated until no more air escapes from the side tube. Then, a graduated tube filled with water is inverted over the side tube dipping in a trough filled with water. A small quantity of substance is weighed exactly in a small stoppered bottle and is dropped in the Victor Meyer's tube and sealed immediately. The bottle falls on the

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pad and its contents suddenly change into vapour, blows out the stopper and displaces an equal volume of air in graduated tube. The volume of air displaced is measured by taking the graduated tube out, closing its mouth with thumb and dipping in a jar filled with water. When water levels inside and outside the tube is equal, the volume of air displaced is noted. The atmospheric pressure and

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicia ...

temperature are noted.

Victor Meyer method of alcohol distinction

Victor Meyer suggested a method for determining the types of

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

i.e. (primary, secondary or tertiary). In this method the sample alcohol is treated with PI₃ to get the iodoalkane which is again treated with AgNO₂ to get the

nitroalkane In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitr ...

. The nitroalkane is then treated with

nitrous acid Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in Solution (chemistry), solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazoni ...

which is obtained by NaNO₂ and

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a spe ...

. The resulting solution is treated with KOH and the colour is observed. The red, blue and no colour indicates the primary, secondary and tertiary alcohol respectively.

References

* *General Chemistry-John Russel by McGraw Hill International Editions 3rd edition *University General Chemistry-An Introduction to Chemical Science edited by CNR Rao by McMillan Indian Ltd. *Inorganic Chemistry, by P.L.Soni *Tamil Nadu State Board class 11 textbook vol.1 page-31. Laboratory equipment {{Physical-chemistry-stub