Module 2854: Chemistry by Design

This module covers the following teaching sections:

AA Aspects of Agriculture

CD Colour by Design

O The Oceans

MD Medicines by Design

VCI Visiting the Chemical Industry

AA Aspects of Agriculture

Learning outcomes

Candidates should be able to:

(a) discuss ways in which chemists can help improve food production, including:

(i) providing extra nutrients,

(ii) controlling soil pH,

(iii) controlling pests; C3.2,C3.3

(b) recall the qualitative effect of temperature on the rate constant of a reaction;

(c) interpret silicate structures in terms of the tetrahedral silicate unit;

(d) interpret properties of clay minerals in terms of a simple model of layers made up of

tetrahedral silicate sheets and octahedral aluminate sheets;

(e) show awareness of the role of ion exchange processes, including those in the soil, and the

influence of ion-exchange characteristics on the properties of different soils;

(f) describe the principles of ion exchange;

(g) relate ion exchange behaviour of anions and cations to ionic size;

(h) explain the factors determining the radii of anions and cations, including atomic number,

charge and hydration, and relate ionic size to properties;

(i) discuss the redox reactions involved in the interconversion of the following species in the

nitrogen cycle:

(i) nitrogen gas,

(ii) nitrate(V) ion,

(iii) nitrate(III) ion,

(iv) ammonium ion,

(v) dinitrogen oxide(N2O), nitrogen monoxide(NO), nitrogen dioxide(NO2);

(j) describe in outline the manufacture of ammonia in the Haber Process, giving essential

conditions;

(k) use given data to evaluate the most economical operating conditions for an industrial

process such as the Haber Process, using principles of equilibrium and rates of reactions;

(l) write an expression for the equilibrium constant, K_p, for reactions involving gases (in terms of

partial pressures);

(m) use values of K_p, together with given data on partial pressures, to carry out simple calculations concerning the composition of equilibrium mixtures;

(n) describe and explain, in terms of structure and bonding, the trends in reactions of the elements and properties of compounds across a period, including:

(i) the reactions of the elements with oxygen, chlorine and water,

(ii) the acid-base character of oxides,

(iii) the behaviour of chlorides towards water;

(o) recall that there is a relationship between the structure and bonding of a substance and its properties, and relate the properties of substances to their structure and bonding;

(p) interpret given data in terms of the structure and bonding of a substance;

(q) describe and explain the partition equilibrium that occurs when a solute is distributed between two immiscible solvents;

(r) explain the role of chemistry in the design of pesticides that combine maximum efficacy with minimum environmental damage.

CD Colour by Design

Learning outcomes

Candidates should be able to:

(a) explain the absorption of ultraviolet light and visible light in terms of transitions between

electronic energy levels;

(b) use ultraviolet (u.v.) and visible spectroscopy to help identify unsaturated organic molecules;

(c) recall that colour changes may be associated with the following chemical changes:

(i) acid-base (indicators),

(ii) ligand exchange,

(iii) redox,

(iv) precipitation,

(v) polymorphism (different crystal structures);

(d) relate the desirable properties of pigments (such as colour shade, colour intensity, fastness to relevant properties);

(e) outline the general principles of gas-liquid chromatography (g.l.c.);

(f) show awareness of the techniques used to identify the materials used in a painting, including:

(i) gas-liquid chromatography,

(ii) atomic emission spectroscopy,

(iii) visible spectroscopy (reflection and transmission);

(g) given relevant information, interpret results from analytical techniques used to identify components of unknown materials, such as those used in paintings;

(h) recall that fats and oils consist mainly of mixed esters of propane-1,2,3-triol with varying degrees of unsaturation;

(i) describe in general terms the process of oxidative cross-linking by which unsaturated oils harden, and relate to their use as media in oil-based paints;

(j) recognise arenes and arene derivatives (aromatic compounds);

(k) relate the characteristic properties of aromatic compounds to the delocalisation of electrons in the benzene ring;

(l) describe and explain the following electrophilic substitution reactions of arenes:

(i) halogenation of the ring,

(ii) nitration,

(iii) sulphonation,

(iv) Friedel-Crafts alkylation,

(v) Friedel-Crafts acylation;

(m) describe and explain the formation of azo dyes by coupling reactions involving diazonium compounds;

(n) describe and explain the structure of a dye molecule in terms of its functional components:

chromophore, groups which modify the chromophore, groups which affect the solubility of the

dye, groups which attach the dye to the fibre;

(o) explain, in terms of intermolecular forces, ionic attractions and covalent bonding, how some dyes attach themselves to fibres;

(p) relate the colour of a dye to the presence of a chromophore, and groups that modify the chromophore, in the dye molecule.

O The Oceans

Learning outcomes

Candidates should be able to:

(a) describe the factors determining the relative solubility of a solute in aqueous and non- aqueous solvents;

(b) explain and use the terms: enthalpy change of solution, lattice enthalpy, enthalpy of solvation (hydration);

(c) describe the solution of an ionic solid in terms of an enthalpy cycle involving enthalpy change of solution, lattice enthalpy and enthalpies of solvation (hydration) of ions;

(d) use enthalpy cycles to perform calculations involving enthalpy change of solution, lattice

enthalpy and enthalpy of solvation (hydration);

(e) interpret the trends in solubility in water of the hydroxides and carbonates of the elements of Group 2 (excluding Be) in terms of lattice enthalpies and enthalpies of hydration of the ions;

(f) construct and use a Born-Haber cycle for a simple ionic compound;

(g) discuss entropy changes in a qualitative manner, interpreting entropy as a measure of the number of ways that molecules and their associated energy quanta can be arranged;

(h) discuss qualitatively the process of dissolving in terms of energy and entropy factors;

(i) interpret the tendency of a process to occur in terms of entropy changes in the system ( Ssys) and surroundings ( Ssurr), and the requirement that the total entropy change ( Stotal) should be positive;

(j) calculate entropy changes using the expression: .S _total = .S _sys + ._{S surr}

(k) compare the following properties of water to those of other liquids, and other hydrides of Group 6 elements, and relate them to molecular structure:

(i) specific heating capacity,

(ii) enthalpy change of vaporisation,

(iii) density changes on melting;

(l) account for the influence of oceans on climate in terms of the characteristic properties of water;

(m) explain and use the following terms: strong acid and strong base, pH;

(n) explain the significance of the ionic product of water, Kw ;

(o) use given data to calculate the pH of solutions of strong acids and strong bases;

(p) explain and use the following terms: weak acid, acidity constant Ka , pKa;

(q) use given data to calculate the pH of solutions of weak acids;

(r) explain the action of buffer solutions;

(s) describe applications of buffer solutions;

(t) use given data to calculate the pH of a buffer solution;

(u) explain and use the term solubility product for simple ionic compounds of formula X n+ Y n-

(v) use solubility products quantitatively to perform calculations concerning dissolving and precipitation processes;

(w) interpret acid-base and precipitation processes in the oceans in terms of Ka and Ksp;

(x) discuss the global influence of the processes occurring when carbon dioxide dissolves in water.

MD Medicines by Design

Learning outcomes

Candidates should be able to:

(a) show awareness of the chemical principles behind methods which can be used to detect ethanol in the body (g.l.c. and i.r. spectroscopy);

(b) describe the following reactions involving aldehydes and ketones:

(i) formation by oxidation of alcohols,

(ii) oxidation to carboxylic acids,

(iii) reduction to alcohols,

(iv) reaction with hydrogen cyanide;

(c) explain the mechanism of the nucleophilic addition reaction between an aldehyde or a ketone and hydrogen cyanide;

(d) describe the structure of a pharmacologically active material in terms of its functional components: pharmacophore and groups which modify the pharmacophore;

(e) relate the action of biologically active chemicals to their interaction with receptor sites;

(f) discuss the factors affecting the way that species interact in three dimensions:

(i) size,

(ii) shape,

(iii) bond formation,

(iv) orientation;

(g) show awareness of the role of chemists in designing and making new compounds for use as pharmaceuticals;

(h) show awareness of the application of computer modelling techniques in the design of medicines;

(i) identify individual functional groups within a polyfunctional molecule, and hence make

predictions about its properties;

(j) use knowledge of organic reactions mentioned elsewhere in these specifications (AS and A2), together with any further given reactions, to devise synthetic routes for preparing organic compounds;

(k) use the following terms to classify organic reactions: hydrolysis, oxidation, reduction, condensation, elimination;

(l) classify organic reactions according to their reactions mechanisms: nucleophilic substitution, electrophilic addition, electrophilic substitution, nucleophilic addition, radical;

(m) use a combination of spectroscopic techniques (m.s., i.r., n.m.r. and u.v. and visible) to elucidate the structure of organic molecules.

Visiting the Chemical Industry

Candidates should be able to:

(a) describe the stages in the manufacture of a new product: research, pilot study, scaling-up, production, review;

(b) describe the characteristics of effective and successful chemical processes in terms of:

(i) raw materials and feedstock,

(ii) batch or continuous process,

(iii) rate, including use of catalysts,

(iv) product yield,

(v) nature of coŒproducts and by-products,

(vi) waste disposal and effluent control,

(vii) location,

(viii) safety,

(ix) cost;

(c) use knowledge and understanding of chemical principles and processes to discuss and evaluate the factors mentioned in (b);

(d) use information concerning the chemical properties of reactants and products to discuss suitable materials for the construction of a chemical plant;

(e) show awareness that control of pollution from chemical plants has economic implications, and discuss associated issues.