Thermodynamics

Define enthalphy of formation

Enthalpy change when one mole of a compound is formed from its elements in their standards states under standard conditions

Define enthalpy of ionisation

The Enthalpy change when one mole of electrons is removed from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

Enthalpy of atomisation of an element

The Enthalpy change for the formation of one mole of gaseous atoms from an element in its standard state

Enthalpy of atomisation of a compound

The enthalphy required to convert one mole of a compound into gaseous atoms

Bond dissociation enthalphy

The Enthalpy required to break one mole of covalent bonds from one mole of a gaseous molecule into atoms

Electron affinity

The Enthalpy change when one mole of electrons is added to a mole of gaseous atoms to form one mole of gaseous 1- ions

Lattice formation Enthalpy

The Enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions under standard conditions

Lattice dissociation Enthalpy

The Enthalpy change when one mole of a solid ionic compound is dissociated into its gaseous ions under standard conditions

Enthalpy of hydration

The Enthalpy change when one mole of aqueous ions is formed from a mole of gaseous ions

Enthalpy of solution

The enthalphy change when one mole of a solid ionic compound is completely dissolved in water to form aqueous ions under standard conditions

Suggest why second electron affinity is an endothermic process 

Repulsion between added electrons and negative ion so requires energy to push them together

Suggest why Enthalpy of lattice dissociation of potassium oxide is less endothermic than that of sodium oxide 

Potassium is a larger positive ion so has a lower charge density than sodium 

Weaker ionic bonds amd electrostatic attraction 

Less energy required to break ionic bonds so less endothermic 

State equation for gibs free energy 

🔼G= 🔼H - T x 🔼S

State the equation when wanting to find out the minimum temperature required for a reaction to occur

🔼=0

Temp = 🔼H/🔼S

State the meaning of the term perfect ionic model 

Ions are 100% spherical with no polarisation of ion or covalent character 

Explain why entropy for co2 is greater than that for carbon (s)

C02 is a gas so is more disordered

State rhetoric temperature at which the standard entropy of aluminium is 0 JK Mol -1

Absolute zero 

0 kelvin 

-273 degrees

What does the Y intercept, Gradient suggest about reaction

Intercept = Enthalpy change

Gradient = entropy change

If negative gradient then negative value for entropy

(Exothermic reaction) Reaction carried out at a higher temperature

Explain how this effects the value of delta G

Delta G more negative

S positive

When is a reaction feasible

When delta G is equal to or less than zero/negative

Define mean bond Enthalpy

Heat energy change required to break one mole of covalent bonds averaged for that bond over a range of molecules

How to calculate entropy 

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