DF  Developing Fuels

DF1 Synopsis

A study of fuels and the contribution that chemists make to the development of better fuels. Main topics:

·         desirable properties of a fuel

·         hydrocarbons and alcohols as fuels

·         available energy in fuels

·         overcoming the problem of auto-ignition: alternatives to lead compounds

·         exhaust emissions and control of exhaust pollutants

·         alternative fuels.

 

DF2 Learning outcomes

Candidates should be able to:

(a)     use the concept of amount of substance to perform calculations involving: volumes of

      gases,  balanced chemical equations, enthalpy changes;

 

(b)     explain and use the terms: exothermic, endothermic, standard state, enthalpy change of combustion, enthalpy change of reaction, enthalpy change of formation;

 

(c)     interpret the pattern of enthalpy changes of combustion for successive members of

 an homologous series;

 

(d)    calculate enthalpy changes from experimental results;

 

(e)     use Hess‘s Law and enthalpy cycles to calculate enthalpy changes;

 

(f)   recall that bond-breaking is an endothermic process and bond-making is exothermic;

 

(g)     explain and use the term: bond enthalpy;

 

(h) relate bond enthalpy to the length and strength of a bond;

 

(i)       recognise members of the following homologous series: alkanes, cycloalkanes,

      alkenes,   arenes, alcohols, ethers;

 

(j)    explain and use the terms: aliphatic, aromatic;

 

 

(k)

use systematic nomenclature to name alkanes and alcohols;

(l)

explain and use the term isomerism;

(m)

recognise structural isomers;

(n)

draw and interpret structural formulae (full, shortened and skeletal);

(o)

relate molecular shape to structural formulae and be familiar with the use of models to represent  molecular shape.

(p)

 

describe and write balanced equations for the combustion (oxidation) of alkanes and alcohols.

(q)

 

describe the effect of chain length and chain branching on the tendency of petrol towards auto-ignition which causes ‘knocking in a car engine.

(r)

 

explain what is meant by the octane number of a petrol and describe how it may be increased.

(s)

 

describe the origin of pollutants from car exhausts: unburnt hydrocarbons, CO, CO2, NOx, SOx, and show awareness of the environmental implications;

(t)

 

explain the formation of nitrogen monoxide (NO) in an internal combustion engine;

(u)

explain and use the terms catalysis, catalyst, catalyst poison;

(v)

outline a simple model to explain the function of a heterogeneous catalyst;

(w)

 

describe  the use of  isomerisation, reforming and cracking reactions to improve the performance of hydrocarbon fuels.

(x)

 

show awareness of the use of catalysts in isomerisation, reforming and cracking processes and in the control of exhaust emissions.

(y)

 

discuss entropy in a qualitative manner, interpreting it as a measure of the number of ways that molecules can be arranged.

(z)

 

show awareness of the differences in magnitude of the entropy of a solid, a liquid, a solution and a gas.

      (aa) discuss the desirable properties of a fuel;

      (bb) show awareness of the work of chemists in improving fuels and in searching for and

             developing fuels for the future: use of oxygenates, the hydrogen economy.