UNIT 1 Section 7 - Thermodynamics

Question 1

What is Lattice enthalpy of formation

Answer 1

The enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions

Question 2

What is Lattice dissociation enthalpy

Answer 2

The enthalpy change when 1 mole of a solid ionic compound is completely dissociated into its gaseous ions

Question 3

What is Enthalpy change of solution

Answer 3

When one mole of a solid ionic substance dissolves in water to produce aqueous ions in an infinitely dilute solution

Question 4

What is Enthalpy of formation

Answer 4

when elements in their standard states form 1 mole of a compound in standard states under standard conditions

Question 5

what factors affect enthalpy of hydration

Answer 5

the partial charges of water that are attracted to the ions

the partial charges of water are more strongly attracted to smaller ions

Question 6

what is the definition of the enthalpy of atomisation

Answer 6

when the elements in their standard states form one mole of gaseous ions

Question 7

what is the enthalpy of hydration

Answer 7

when 1 mole of aqueous ions is formed from gaseous ions

Question 8

what factors can produce covalent character

Answer 8

small highly charged positive ions in the lattice

large highly charged negative ions

Question 9

what properties does covalent character affect

Answer 9

the solubility (less) and the conductive ability (less)

Question 10

what is entropy

Answer 10

the measure of disorder or randomness in a system

Question 11

factors that affect entropy

Answer 11

1. state matter
2. energy of the particles
3. dissolving the substance
4. number of particals

Question 12

when is a reaction feasible

Answer 12

when the delta G=0

Question 13

what is ionisation energy

Answer 13

the amount of energy required to remove one mole of electrons from one mole of gaseous ions

Question 14

what is enthalpy of atomisation

Answer 14

enthalpy change when 1 mole of gaseous atoms is formed from its element under standard conditions

Question 15

what is Kp

Answer 15

the ratio of products and reactant concentration in terms of their paritial pressuresi

Question 16

what is the equation for Kp

Answer 16

Kp= (ppc)y x (ppd)z
———————–
(ppa)w x (ppb) x

Question 17

what is the equation for partial pressures

Answer 17

pp = mole fraction x total pressure

Question 18

what is the mole fraction

Answer 18

no. moles of species / total number of moles of all species

Question 19

what are the factors that effect lattice enthalpy

Answer 19

radius- the smaller the ion the stronger the bonds

charge- the higher the charge the stronger the bonds

Question 20

what does a reaction being feasible mean

Answer 20

that once the reaction has started it will carry onto completion without energy being supplied to it

Question 21

what is the equation for entropy change

Answer 21

enthalpy change= S products- S reactants

Question 22

what is the free energy change equation

Answer 22

free energy change = enthalpy change - TdeltaS

Question 23

what are the units for the free energy change equation

Answer 23

temperature = kelvin
delta G = j/mol
delta S = J/K/mol

Question 24

if delta H and delta S are both positive what is the feasibility like

Answer 24

low temps not feasible
high temps are feasible

Question 25

if delta H is negative and delta S is negative what is the feasibility like

Answer 25

Low temps feasible
High temp not feasible

Question 26

if delta H is positive and delta S is positive what is the feasibility like

Answer 26

Low temps not feasible
High temp feasible

Question 27

if delta H is positive and delta S is negative what is the feasibility like

Answer 27

never feasible