F331 - Chemistry for life - Module 2 - (DF) Developing Fuels - Energetics


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, (standard) enthalpy change of combustion (ΔHc), (standard) enthalpy change of reaction (ΔHr), (standard) enthalpy change of formation (ΔHf)

(c) describe and design simple experiments to measure the energy transferred when reactions occur in solution or when flammable liquids burn; explain the limitations of such practical procedures and the uncertainties of measurement involved

(d) calculate enthalpy changes from experimental results, recalling the formula:

heat transferred = mass × specific heat capacity × temperature change;

describe the approximations in density and specific heat capacity of solutions made in these calculations

(e) use Hess' law to explain how enthalpy cycles can be used to calculate enthalpy changes of reaction, including via enthalpy changes of formation, combustion and bond enthalpies

carry out these calculations;

(f) explain and use the term (average) bond enthalpy and relate bond enthalpy to the length and strength of a bond

recall that bond-breaking is an endothermic process and bond-making is exothermic and use these ideas to explain the overall enthalpy change for a reaction

(g) use the term entropy in a qualitative manner, interpreting it as a measure of the number of ways that molecules can be arranged

(h) describe the differences in magnitude of the entropy of a solid, a liquid, a solution and a gas