enthalpy change definitions

Question 1

standard lattice enthalpy

Answer 1

the enthalpy change when 1 mole of an ionic lattice is formed from its gaseous ions under standard conditions. this value is always exothermic

Question 2

standard enthalpy change of formation

Answer 2

the enthalpy change that takes place when 1 mole of a compound is formed from its elements under standard conditions, with all reactants and products in their standard states as well. it can have either an exothermic or endothermic value

Question 3

standard enthalpy change of atomisation

Answer 3

the enthalpy change that takes place for the formation of 1 mole of gaseous atoms from the element in its standard state under standard conditions. this value is always endothermic

Question 4

first ionisation energy

Answer 4

the enthalpy change required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions . this value is always endothermic

Question 5

first electron affinity

Answer 5

the enthalpy change that takes place when 1 electron is added to each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1- ions this value is usually exothermic. second electron affinities always have an endothermic value

Question 6

standard enthalpy change of solution

Answer 6

the enthalpy change that takes place when 1 mole of a solute dissolves in a solvent

Question 7

enthalpy change of hydration

Answer 7

the enthalpy change that accompanies the dissolving of gaseous ions in water to produce 1 mole of aqueous ions

Question 8

what happens when an ionic lattice dissolves in water

Answer 8

bonds between the ionic lattice break to form a gas. bonds between the gaseous ions and the water are made

Question 9

standard enthalpy change of reaction

Answer 9

the enthalpy change when the reaction occurs in the molar quantities shown in the chemical equation under standard conditions

Question 10

standard enthalpy change of formation

Answer 10

the enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions

Question 11

standard enthalpy change of combustion

Answer 11

the enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions

Question 12

enthalpy change of neutralisation

Answer 12

the enthalpy change when an acid and alkali react together , under standard conditions to form 1 mole of water