A-level Chemistry/OCR (Salters)/Colour by Design/Check Your Notes
Colour By Design!
What you should know!!
- Absorption of ultraviolet light and visible light in terms of transitions between electronic energy levels.
- Use of ultraviolet (u.v.) and visible spectroscopy to help identify unsaturated organic molecules.
- Colour changes associated with the following types of chemical changes: acid-base (indicators), ligand exchange, redox, precipitation and polymorphism (different crystal structures).
- The relationship between the properties of pigments (colour shade, colour intensity, fastness) to relevant properties (Storyline CD2 and CD3).
- General principles of gas-liquid chromatography (g.l.c.)
- Techniques used to identify the materials used in a painting, including the use of g.l.c. atomic emission spectroscopy, visible spectroscopy (reflection and transmission) (Storyline CD3 and CD4; Activities CD4.1 to CD4.5).
- Nature of fats and oils as mixed esters of propane-1,2,3-triol with varying degrees of unsaturation.
- An outline of the process of oxidative cross-linking by which unsaturated oils harden; the relationship of this process to their use as media in oil-based paints.
- What arenes and arene derivatives (aromatic compounds) are.
- Structure of benzene.
- How the characteristic properties of aromatic compounds arise from the delocalisation of electrons.
- Following electrophilic substitution reactions of arenes: halogenation of the ring, nitration, sulphonation, Friedel-Crafts alkylation and Friedel-Crafts acylation.
- Formation of azo dyes by coupling reactions involving diazonium compounds.
- Structure of a dye molecule in terms of its various components: chromophore, groups which modify the chromophore, groups which made the dye more soluble in water and groups which attach the dye to the fibre (Storyline CD5 to CD7).
- Ways in which dyes attach themselves to fabrics: weak intermolecular forces, hydrogen bonds, ionic attractions and covalent bonding (Storyline CD7; Activity CD7.2).
- Relationship between the colour of a dye and the presence of a chromophore, and groups that modify the chromophore, in the dye molecule.
- Relationship between colour in materials and transitions between electronic energy levels.