Key Definitions - EEE

Question 1

Rate of Reaction

Answer 1

Change in concentration of a reactant or product per unit time.

Question 2

Initial rate of reaction

Answer 2

Change in concentration of reactant or product when t=0

Question 3

Order of reaction

Answer 3

Power to which the concentration is raised in the rate equation

Question 4

Overall order

Answer 4

Sum of the individual orders

Question 5

Rate constant

Answer 5

links rate of reaction with the concentration of reactants raised to the power of their orders in the rate equation

Question 6

Half life

Answer 6

The time taken for a reactant’s concentration to reduce by half

Question 7

Reaction mechanism

Answer 7

series of steps which make up the overall reaction

Question 8

Rate determining step

Answer 8

slowest step in a multi step reaction

Question 9

Intermediate

Answer 9

A species formed in one step of a multi step reaction and consumed in a subsequent step, such that it is not seen in the overall equation

Question 10

Dynamic Equilibrium

Answer 10

exists in a closed system when the rate of reaction in forward direction is equal to rate of reaction in the reverse

Question 11

Homogeneous Equilibrium

Answer 11

all reactants and products in the same physical state

Question 12

Heterogeneous equilibrium

Answer 12

reactants and products in equilibrium in different physical states

Question 13

Neutralisation

Answer 13

Chemical reaction when acid and base react to produce salt + H2O

Question 14

Acid-Base pair

Answer 14

two species which are related to each other by gaining or loosing a proton

Question 15

pH

Answer 15

-log[H+]

Question 16

[H+]

Answer 16

10^-pH

Question 17

Ka

Answer 17

([H+][A-})/[HA]

Question 18

pKa

Answer 18

-logKa

Question 19

Ka

Answer 19

10^-pKa

Question 20

Ionic product of water

Answer 20

[H+][OH-] = 1x10^-14

ionic product - multiply the concentrations of ions in water

Question 21

Buffer solution

Answer 21

mixture that minimises pH change on addition of small amounts of acid or base

Question 22

Equivalence point

Answer 22

point in titration at which volume of one solution has reacted completely with volume of the second, matching stoichiometry

Question 23

end point

Answer 23

equal concentrations of weak acid/conjugate base forms of the indicator. Colour is midway between colours for acid and base

Question 24

Standard enthalpy change of neutralisation

Answer 24

energy change accompanying the neutralisation of aqueous acid with aqueous base to form one mole of H2O under standard conditions

Question 25

Lattice enthalpy

Answer 25

Enthalpy change that accompanies the formation of one mole of ionic lattice from its gaseous ions under standard conditions

Question 26

Hess’s Law

Answer 26

If a reaction can proceed by multiple routes, with the initial and final conditions the same, the total enthalpy change is the same for each route

Question 27

Standard enthalpy change of formation

Answer 27

enthalpy change accompanying formation of one mole of compound from its constituent elements in the standard states under standard conditions

Question 28

enthalpy change of atomisation

Answer 28

enthalpy change accompanying the formation of one mole of gaseous atoms from the element in its standard state

Question 29

First ionisation energy

Answer 29

enthalpy change accompanying the removal of one electron from each atom in one mole of a gaseous atoms to form one mole of 1+ ions

Question 30

Second ionisation energy

Answer 30

enthalpy change accompanying the removal of one electron from each ion in one mole of 1+ ions to form one mole of 2+ ions

Question 31

First electron affinity

Answer 31

enthalpy change accompanying the addition of one electron to each atom in one mole of gaseous atoms to produce one mole of gaseous 1- ions

Question 32

Second electron affinity

Answer 32

enthalpy change accompanying the addition of one electron to each 1- ion in one mole of gaseous ions to form one mole of gaseous 2- ions

Question 33

Standard enthalpy change of solution

Answer 33

enthalpy change that accompanies dissolving one mole of an ionic compound completely in water under standard conditions to form one mole of aqueous
ions.

Question 34

Standard enthalpy change of hydration

Answer 34

enthalpy change accompanying dissolving one mole of gaseous atoms in water forming one mole of aqueous ions under standard conditions

Question 35

Entropy

Answer 35

Quantitative measure of order or disorder in a system

Question 36

Standard entropy change of reaction

Answer 36

entropy change that accompanies reaction in molar quantities expressed in equation under standard conditions in standard states

Question 37

Free energy change

Answer 37

Balance between enthalpy, entropy and temperature for a process:G=H-TS

T is measured in K, and reactions are spontaneous if G

Question 38

Oxidation

Answer 38

Loss of electrons/increase in oxidation number

Question 39

Reduction

Answer 39

Gain of electrons, decrease in oxidation number

Question 40

Standard electrode potential

Answer 40

EMF that exists between a given half cell and standard hydrogen electrode under standard conditions of 1 molem-3, 1 atm and 298k

Question 41

Transition element

Answer 41

D-block element that can form one or more ions with an incomplete d sub-shell

Question 42

Complex ion

Answer 42

Transition metal ion covalently bonded to one or more ligands

Question 43

Ligand

Answer 43

Species that can donate a lone pair of electrons to a central transition metal ion to form a new co-ordinate bond

Question 44

CO-ordination number

Answer 44

The number of co-ordinate bonds between a central transition metal ion and its linands

Question 45

Stereoisomerism

Answer 45

species with same structural formula but a different arrangement in space

Question 46

Ligand substitution

Answer 46

A reaction in which one ligand replaces another in a complex

Question 47

Stability constant, KStab

Answer 47

equilibrium constant for transition metal surrounded by water ligands compared to having undergone total ligand substitution