A question and answer sheet to test learner’s knowledge of thermodynamics

The topics covered in this Starter for ten are: important definitions, Born-Haber cycles, enthalpy of solution, entropy, and Gibbs free energy.

## Example questions

For each of the transformations represented by the equations 1-5, name the enthalpy change and provide a full definition.

e.g. ½ N2(g) + 3/2 H2(g) → NH3(g)

Name: The standard molar enthalpy change of formation of ammonia

Definition: The enthalpy change when one mole of a compound is formed from its elements under standard conditions, all reactants and products in their standard states

1. O-(g) + 1 e-(g) → O2-(g)

Name:

Definition:

2. K+(g) + aq → K+(aq)

Name:

Definition:

3. NaCl(s) + aq → Na+(aq) + Cl-(aq)

Name:

Definition:

4. Mg2+(g) + O2-(g) → MgO(s)

Name:

Definition:

5. HCl(g) → H+(g) + Cl-(g)

Name:

Definition:

In 1918, a chance meeting of two German scientists, Max Born and Fritz Haber led to a discussion of the manner in which an ionic compound is formed when a metal reacts with a non-metal. This resulted in the creation of what we know today as Born Haber cycles.

The Born Haber cycle for the formation of calcium oxide is shown in the diagram below;

1. Complete the cycle by adding suitable labels for the one missing enthalpy change and the missing intermediate species on the three stages labelled A-C.
2. Explain why the second electron affinity of oxygen is positive.
3. Use the values for the enthalpy changes given to calculate the lattice dissociation enthalpy for calcium oxide.

## Notes

This question and answer sheet is available from the ‘Downloads’ section below. an editable version is also available.