Ded

Question 1

Enthalpy change

Answer 1

The amount of heat energy take in or given during any change in a system

Question 2

Enthalpy change of reaction

Answer 2

The Enthalpy change when the number of moles of reactants as specified in the balanced equation reacts

Question 3

The standard Enthalpy change of reaction

Answer 3

The Enthalpy change when one mole of the compound is formed from its element under standard conditions, all reactants and products in their standard states

Question 4

Standard Enthalpy change of combustion

Answer 4

The enthalpy change that occurs when one mole of a substance is combusted completely in oxygen under standard conditions all in standard states

Question 5

Enthalpy change of atomisation

Answer 5

The enthalpy change when one mole of gaseous atoms is formed from the element in it’s standard state

Question 6

Bond dissociation Enthalpy(bond energy)

Answer 6

The standard molar enthalpy change when one mole of a covalent bond is broken into two gaseous atoms

Question 7

First ionisation enthalpy

Answer 7

The first ionisation enthalpy is the enthalpy change required to remove 1 mole of electrons with 1 mole of gaseous atoms to form 1 mole of gaseous ions with a +1 charge

Question 8

Second ionisation enthalpy

Answer 8

The enthalpy change to remove one mole of electrons from one mole of gaseous 1+ ions to produce one mole of gaseous 2+ ions

Question 9

First electron affinity

Answer 9

The enthalpy change that occurs when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a -1 charge

Question 10

Second electron affinity

Answer 10

The second electron affinity is the enthalpy change when one mole of gaseous 1- ions gains one electron per ion to produce gaseous 2-ions

Question 11

Enthalpy change of first and second electron affinity and why

Answer 11

First is negative because of nuclear charge and electron attraction and it is more stable so exothermic
Second is positive because of electron repulsion between negative ion and electron so endothermic

Question 12

Enthalpy of lattice formation

Answer 12

The standard Enthalpy change when 1 mole of an ionic crystal lattice is formed from its constituent ions in gaseous form

Question 13

Enthalpy of hydration

Answer 13

When one mole of gaseous ions become aqueous ions

Question 14

Enthalpy of solution

Answer 14

The enthalpy of solution is the standard enthalpy change when one mole of an ionic solid dissolves in a large enough amount of water to ensure that the dissolved ions are well separated and do not interact with one another

Question 15

Electron affinity trends

Answer 15

Up a group and across a period and becomes more exothermic

Question 16

Exothermic

Answer 16

When energy is transferred from the system to the surrounding, the products have less energy than the reactants

Question 17

Endothermic

Answer 17

Energy is transferred from the surrounding to the system, products have more energy than the reactants

Question 18

Enthalpy change of neutralisation

Answer 18

The enthalpy change when solutions of an acid and and alkali react together under standard conditions to produce one mole of water

Question 19

Entropy

Answer 19

A thermodynamic quantity which is a measure of the degree of disorder within any system. The greater the degree of disorder then the higher the entropy is

Question 20

Gibb’s free energy change

Answer 20

The thermodynamic quantity which allows predictions to be made as to whether a chemical reaction is possible. A possible chemical reaction will have a negative value

Question 21

Spontaneous reaction

Answer 21

A reaction that occurs without outside help

Question 22

Activation energy

Answer 22

The energy, in excess over the ground state, which must be added to an atomic or molecular system to allow a particular process to take place

Question 23

Ion polarisation

Answer 23

Positive cation attracts the electrons in the anion towards it and distorts the electron cloud of the anion

Question 24

Charge density

Answer 24

The measure of electric charge per unit area