Organic Analysis Practice Flashcards

A complete set of vocabulary flashcards based on the organic analysis lecture notes, covering test-tube reactions, mass spectrometry, and infrared spectroscopy.

Alkene chemical test

Shake the compound with bromine water; the observation for a positive result is that the orange colour disappears.

Halogenoalkane chemical test

1. Add $NaOH(aq)$ and warm; 2. Acidify with $HNO_{3}$; 3. Add $AgNO_{3}(aq)$. The result is a precipitate of $AgX$.

Alcohol (primary or secondary) chemical test

Add acidified $K_{2}Cr_{2}O_{7}$; the orange colour turns green. This also occurs with aldehydes.

Aldehyde test (Fehling's)

Warm the compound with Fehling's solution; the blue colour turns to a red precipitate.

Aldehyde test (Tollens')

Warm the compound with Tollens' solution; a silver mirror forms.

Carboxylic acid chemical test

Add $NaHCO_{3}(aq)$; the observation is that $CO_{2}$ is given off (fizzing).

Mass Spectrometry (MS)

The main method for finding the relative molecular mass of organic compounds by measuring the time of flight of positive ions.

m/z

The mass to charge ratio, which constitutes the horizontal axis of a mass spectrum graph.

Molecular ion ($M^{+}$)

The ion formed when a molecule loses an electron in a mass spectrometer; it represents the relative mass of the molecule.

Fragmentation

The process where molecular ions break up into smaller fragment ions as they pass through the mass spectrometer, providing a 'fingerprint' for identification.

$^{13}C$ isotope peak

A tiny peak found one mass unit to the right of the molecular ion in an organic mass spectrum.

Gas Chromatography Mass Spectrometry (GCMS)

A technique combining gas chromatography to separate mixtures and mass spectrometry to identify components; used in forensics and drug testing.

Gas Chromatography

A separation technique that uses a stream of gas to carry a mixture of vapours through a column packed with a powdered solid.

High resolution mass spectrometry

A method that measures masses to three or four decimal places, allowing for the determination of a precise molecular formula.

Infrared (IR) spectroscopy

An analytical technique that uses the absorption of infrared radiation by-chemical bonds to identify functional groups.

Transmittance

A measure of the intensity of radiation emerging from a sample in an infrared spectrometer, plotted on the vertical axis.

Wavenumber

A unit proportional to frequency used in infrared spectra, measured in $cm^{-1}$.

Fingerprint region

The area of an infrared spectrum below approximately $1500\,cm^{-1}$ which is unique to a particular substance.

O-H bond absorption (alcohols)

Produces a broad peak in an infrared spectrum at a wavenumber between $3230\,cm^{-1}$ and $3550\,cm^{-1}$.

O-H bond absorption (carboxylic acids)

Produces a very broad peak in an infrared spectrum between $2500\,cm^{-1}$ and $3000\,cm^{-1}$.

C=O bond absorption

Produces a peak in an infrared spectrum between $1680\,cm^{-1}$ and $1750\,cm^{-1}$, common in aldehydes, ketones, and carboxylic acids.