Chemguide: Support for CIE A level Chemistry

Learning outcome 5.2(a)

This statement is concerned with enthalpy calculations using simple energy cycles.

It is in several parts:

  • There is a general statement which deals with Hess's Law.

  • Part (i) deals with simple Hess's Law cycles.

  • Part (ii) deals with bond enthalpy calculations.

  • Parts (iii) and (iv) deal with lattice enthalpy and enthalpy changes of solution. You will find that these statements are in bold type in the syllabus, which means that they will only be examined at the end of a 2 year course.

Before you go on, you should find and read the statement in your copy of the syllabus.

Introduction and Part (a)(i)

You will find an introduction to Hess's Law and simple energy cycles on the Chemguide page Hess's Law and enthalpy change calculations. But this is only an introduction, and you will have to find a source of practice questions such as my chemistry calculations book.

Part (a)(ii)

You will find an introduction to bond enthalpy calculations on the Chemguide page bond enthalpy (bond energy).

Parts (a)(iii) and (iv)

The formation of simple ionic solids (from Part (iii)) and Born-Haber cycles (from Part (iv)) are on the Chemguide page lattice enthalpy.

The formation of solutions (from Part (iii)) is on the Chemguide page enthalpies of solution and hydration.

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© Jim Clark 2010 (last modified April 2017)