Enthalpy changes

What is enthalpy of formation?

Enthalpy change to form one mol of a compound from it’s elemental state in standard conditions

When is e of formation exothermic?

When less energy is required to break the bonds than energy released when new bonds form

When is e of formation endothermic?

If more energy is required to break bonds than the energy released when new bonds form

What is an equation representing enthalpy of formation?

What is enthalpy of atomisation?

Enthalpy change when 1 mole of gaseous atoms is produced from an element in it’s standard state

Why is e of atomisation endothermic?

Energy required to break bonds to form individual atoms and to turn solids or liquids into a gas

What is an equation representing enthalpy change of atomisation?

½ I² (s) = I (g)

What is enthalpy of ionisation?

Enthalpy change when every atom in one mole of gaseous atoms loses an electron

Why is e of ionisation endothermic?

Energy required to break the electrostatic attraction between the protons and electron being removed

What is an equation to represent the enthalpy of ionisation?

What is enthalpy of electron affinity?

Enthalpy change where every atom in 1 mol of gaseous atoms gains an electron

Why is the 1st enthalpy of electron affinity exothermic?

Electrostatic attraction made between the electrons and protons in the nucleus

Why is the 2nd enthalpy of electron affinity endothermic?

The negative ion and electron being added repel

What is an equation representing enthalpy of electron affinity?

What is lattice enthalpy?

Enthalpy change when 1 mol of an ionic compound is produced from it’s gaseous ions under standard conditions

Why is lattice enthalpy exothermic?

Energy is released when the ionic bond is formed between the gaseous ions to form the solid ionic compound

What is an equation representing lattice enthalpy?

What is enthalpy of solution?

Enthalpy change when 1 mole of solute dissolves in a sufficient volume of water

When is enthalpy of solution endothermic?

More energy is required to break the bonds in the compound than the energy released when new bonds form between ions and water molecules

When is enthalpy of solution exothermic?

Less energy is required to break the bonds in the compound than the energy released when new bonds form between ions and water molecules

What is an equation representing enthalpy of solution?

What is enthalpy of hydration?

Enthalpy change when gaseous ions dissolve in water to form one mole of aqueous ions

Why is enthalpy of hydration exothermic?

Releasing energy when bonds form between ions and water molecules

How do you find △Le?

Rearrange the equation which gives you △Hf. △Hf = △Le + △Hat + △Hi + △HEa

How to work out △HHyd?

△Hsol + △HLe

What do upwards arrows represent?

Endothermic processes