A level Chemistry OCR B WM

Acid Anhydride

A compound with the functional group R-(CO)O(CO)-R’.

Aldehyde

A compound containing the -CHO functional group at the end of an alkyl chain. Aldehydes can be oxidised to carboxylic acids using Cr₂O₇^2-/H⁺.

Carboxylic Acid

An organic compound containing the -COOH functional group. Carboxylic acids can be formed from the oxidation of primary alcohols using Cr₂O₇^2-/H⁺ and reflux conditions.

Ester

A compound containing the R-COO_R’ functional group (where R and R’ are alkyl groups). Formed by the condensation reaction between a carboxylic acid and an alcohol.

Ether

A compound containing the functional group R-O-R’

Homologous Series

A series of compounds with the same functional group and similar chemical properties. For example, all alkanes belong to the same homologous series.

Ketone

An organic compound containing the C=O functional group in the middle of the alkyl chain. Ketones can be formed by the oxidation of a secondary alcohol.

Phenol

Phenol has an aromatic ring with an OH group attached. A weak acid that reacts with NaOH but not carbonates. Phenol can undergo electrophilic substitution reactions more easily as the lone pair in the p-orbital of oxygen is donated into the π system of phenol, increasing its electron density. As a result of this electron donation, phenol is more susceptible to electrophilic attack than benzene.

Primary Alcohol

An alcohol in which the -OH is attached to a primary carbon atom. Primary alcohols can be oxidised to form either an aldehyde or a carboxylic acid, depending on the conditions.

Secondary Alcohol

An alcohol in which the -OH is attached to a secondary carbon atom. Secondary alcohols can be oxidised under reflux with Cr₂O₇^2-/H⁺ to form a ketone.

Tertiary Alcohol

An alcohol in which the -Oh is attached to a tertiary carbon atom. Tertiary alcohols can’t be oxidised.

Acid

Compounds that release H⁺ ions in aqueous solution.

Dehydration

A reaction that involves a loss of water from the reacting molecules. It is the reverse reaction of hydration.

Distillation

A technique in which liquid is heated then the vapour is cooled and collected in a separate flask to the original mixture.

Esterification

The process of making esters. Esters can be made by a reaction between carboxylic acids and alcohols in the presence of an acid catalyst or by a reaction between acid anhydrides and alcohols.

Filtration Under Reduced Pressure

A technique used to separate and dry an organic solid. A Buchner funnel is inserted into the top of a side-arm flask and a vacuum is applied. The solution is poured onto filter paper in the Buchner funnel so that the solid product can be seperated.

Functional group

An atom/group of atoms responsible for the characteristic reactions of a compound.

Green Chemistry

An area of science which has the aim of being sustainable and limiting the use or production of hazardous substances.

Halogenoalkanes

An organic compound containing a halogen atom (F/Cl/Br/I) bonded to an alkyl chain. Haloalkanes can be formed from alcohols via a substitution reaction with halide ions in the presence of acid.

Melting Point Apparatus

A piece of apparatus used to determine the melting point of a sample. The recorded melting point range is compared with known values to determine whether the sample is pure.

Oxidation

The loss of electrons leading to an increase in oxidation number.

Quickfit Apparatus

Glassware that easily fits together in a variety of arrangements. It is commonly used in organic chemistry for conducting experiments involving distillation, refluxing, and extraction.

Recrystallisation

A technique used to purify an organic solid. The sample is dissolved in the minimum volume of hot solvent and filtered. The filtrate is then cooled before being filtered under reduced pressure. The purified solid will collect on the filter paper in the Buchner funnel.

Reflux

The continual boiling and condensing of a reaction mixture. This is to ensure that the reaction goes to completion. During reflux, the condenser must be positioned vertically.

Separating Funnel

A piece of apparatus that is used to purify an organic liquid by removing the organic layer from an aqueous layer. Allows liquids with different densities to be seperated.

Substitution

A reaction in which one atom/ group of atoms replace another.

Synthetic Route

The series of reactions and steps necessary to obtain a desired product from starting materials.

Thin Layer Chromatography

A technique used to separate mixtures. The stationary phase is a thin layer of alumina or silica fixed to a metal or glass plate. The plate is dotted with the mixture and placed in a beaker of solvent which is allowed to travel up the plate. The mixture separates due to the components having different solubilities in the mobile phase.

Elimination

A type of reaction in which two atoms/groups of atoms are removed from a molecule.

Elemental Analysis

A sample is analysed to determine the proportion of elements that make up the compound present. This is done by converting a known amount of an unknown sample into simple known compounds.

Fragment Ions

Smaller ions formed when an unstable molecular ion breaks down during mass spectrometry.

Fragmentation

During mass spectrometry, unstable molecular ions break down into smaller fragments.

Infrared Radiation

A type of electromagnetic radiation that is absorbed by covalent bonds, causing them to vibrate at a specific frequency.

Infrared Spectroscopy

A technique used to identify particular bonds and functional groups within a molecule. This technique has been used to link global warming with increased energy usage as atmospheric gases containing C=O, O-H and C-H bonds (such as CO₂, H₂O and CH₄) show distinct peaks on the IR spectra.

Mass Spectrometry

A technique used to identify compounds and determine their relative molecular mass.

Molecular Formula

The total number of atoms of each element in the compound.

Molecular Ion Peak

The peak on a mass spectrum with the highest m/z value used to determine molecular mass of a compound.

M⁺¹ Peak

A small peak on a mass spectrum caused by the presence of a small proportion of carbon-13.

M/Z Ratio

The mass to charge ratio on a mass spectrum.