A-Level Chemistry Specification

OCR B H433

Section DF: Developing fuels

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#DF(a)

the concept of amount of substance in performing calculations involving: volumes of gases (including the ideal gas equation \(pV = nRT\)), balanced chemical equations, enthalpy changes;
the techniques and procedures used in experiments to measure volumes of gases

The molar gas volume at room temperature and pressure, RTP (24.0 dm3 mol-1) and the gas constant R (8.314 J mol-1 K-1) are given on the Data Sheet.

#DF(b)

the bonding in organic compounds in terms of σ- and π-bonds

#DF(c)

the relation of molecular shape to structural formulae and the use of solid and dashed wedges to represent 3-D shape

#DF(d)

the terms: exothermic, endothermic, standard conditions, (standard) enthalpy change of reaction (∆rH), (standard) enthalpy change of combustion (∆cH), (standard) enthalpy change of formation (∆fH), (standard) enthalpy change of neutralisation (∆neutH)

Enthalpy change of neutralisation is per mole of water formed.

#DF(e)

the term average bond enthalpy and the relation of bond enthalpy to the length and strength of a bond;
bond-breaking as an endothermic process and bond-making as exothermic;
the relation of these processes to the overall enthalpy change for a reaction

Understanding of the meaning of ‘average’ in this context is required.

#DF(f)

techniques and procedures for measuring the energy transferred when reactions occur in solution (or solids reacting with solutions) or when flammable liquids burn;
the calculation of enthalpy changes from experimental results

Using the formula: \(q = mc∆T\)

#DF(g)

the determination of enthalpy changes of reaction from enthalpy cycles and enthalpy level diagrams based on Hess’ law

Including via enthalpy changes of formation, combustion and bond enthalpies.
A statement of Hess’ law is not required.

#DF(h)

the terms catalyst, catalysis, catalyst poison, heterogeneous

See also OZ(g).

#DF(i)

a simple model to explain the function of a heterogeneous catalyst

#DF(j)

the term cracking;
the use of catalysts in cracking processes;
techniques and procedures for cracking a hydrocarbon vapour over a heated catalyst

Specific examples of catalysts are not required

#DF(k)

the origin of atmospheric pollutants from a variety of sources: particulates, unburnt hydrocarbons, CO, CO2, NOx, SOx;
the environmental implications and methods of reducing these pollutants

#DF(l)

the terms aliphatic, aromatic, arene, saturated, unsaturated, functional group and homologous series

Arenes defined here as compounds containing groups represented as either of:

Unsaturated compounds contain C=C or C≡C.

#DF(m)

the nomenclature, general formulae and structural formulae for alkanes, cycloalkanes, alkenes and alcohols (names up to ten carbon atoms)

#DF(n)

the nomenclature, general formulae and structural formulae for alkanes, cycloalkanes, alkenes and alcohols (names up to ten carbon atoms) balanced equations for the combustion and incomplete combustion (oxidation) of alkanes, cycloalkanes, alkenes and alcohols

#DF(o)

the addition reactions of alkenes with the following, showing the greater reactivity of the C=C bond compared with C–C:

(i) bromine to give a dibromo compound, including techniques and procedures for testing compounds for unsaturation using bromine water
(ii) hydrogen bromide to give a bromo compound
(iii) hydrogen in the presence of a catalyst to give an alkane (Ni with heat and pressure or Pt at room temperature and pressure)
(iv) water in the presence of a catalyst to give an alcohol (concentrated H2SO4, then add water; or steam/H3PO4/heat and pressure)

See also CD(f)

#DF(p)

addition polymerisation and the relationship between the structural formula of the addition polymer formed from given monomer(s), and vice versa

#DF(q)

the terms addition, electrophile, carbocation;
the mechanism of electrophilic addition to alkenes using ‘curly arrows’;
how the products obtained when other anions are present can be used to confirm the model of the mechanism

Either a carbocation or a bromonium ion may be shown for bromination.

#DF(r)

structural formulae (full, shortened and skeletal)

#DF(s)

structural isomerism and structural isomers

#DF(t)

stereoisomerism in terms of lack of free rotation about C=C bonds when the groups on each carbon differ;
description and naming as:

(i) E/Z for compounds that have an H on each carbon of C=C
(ii) cis/trans for compounds in which one of the groups on each carbon of C=C is the same

Knowledge of Cahn-Ingold-Prelog (CIP) priority rules will not be required.

#DF(u)

the benefits and risks associated with using fossil fuels and alternative fuels (biofuels and hydrogen);
making decisions about ensuring a sustainable energy supply.

If comparison with other energy sources is needed, suitable information will be given.