EEE Definitions

Question 1

Rate of reaction

Answer 1

The change in concentration of a reactant or product per unit time

Question 2

Initial rate of reaction

Answer 2

The change in concentration of a reactant, or product per unit time at the start of the reaction when t=0

Question 3

Order with respect to a reactant

Answer 3

The power to which the concentration is raised in the rate equation

Question 4

Overall order of a reaction

Answer 4

The sum of the individual orders

Question 5

The rate constant, k

Answer 5

The constant that links the rate of reaction with the concentration of the reactants raised to the powers of their orders in the rate equation

Question 6

Half life of a reactant

Answer 6

The time taken for the concentration of the reactant to halve

Question 7

Reaction mechanism

Answer 7

A series of steps that together, make up the overall reaction

Question 8

Rate-determining step

Answer 8

The slowest step in the reaction mechanism of a multi-step reaction

Question 9

Dynamic equilibrium

Answer 9

The equilibrium that exists in a closed system when the rate of the forawrd reaction is equal to the rate of the reverse reaction

Question 10

Homogeneous equilibrium

Answer 10

An equilibrium in which all the species making up the reactants and products are in the same physical state

Question 11

Heterogeneous equilibrium

Answer 11

An equilibrium in which all the species making up the reactants and products are in the different physical state

Question 12

Neutralisation

Answer 12

A reaction in which an acid and a base react together to form water and a salt

Question 13

Acid-base pair

Answer 13

A pair of two species that transform into each other by gain or loss of a proton

Question 14

Strong acid

Answer 14

An acid that completely dissociates in solution

Question 15

Weak acid

Answer 15

An acid that partially dissociates in solution

Question 16

Buffer solution

Answer 16

A mixture that minimizes pH changes on addition of small amounts of acid or base

Question 17

Equivalence point

Answer 17

The point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution matching the stoichiometry of the reaction taking place

Question 18

End point

Answer 18

The point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator

Question 19

Standard enthalpy change of neutralisation

Answer 19

The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O under standard conditions

Question 20

Lattice enthalpy

Answer 20

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

Question 21

Standard enthalpy change of formation

Answer 21

The enthalpy change that take place when one mole of a compound is formed from its constituent elements under standard conditions

Question 22

Enthalpy change of atomisation

Answer 22

Enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state

Question 23

Standard enthalpy charge of solution

Answer 23

Enthalpy change that takes place when one mole of a compound is completely dissolves in water under standard condtions

Question 24

Standard enthalpy change of hydration

Answer 24

The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions

Question 25

Entropy

Answer 25

The quantitative measure of the degree of disorder in a system

Question 26

Standard entropy change of reaction

Answer 26

The entropy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

Question 27

Free energy change

Answer 27

The balance between enthalpy, entropy and temperature for a process: ΔG = ΔH - TΔS

A process can take place spontaneously when ΔG < 0

Question 28

Standard electrode potential of a half cell

Answer 28

The e.m.f of a half cell compared with a standard hydrogen half cell measured at 298 K with solution concentrations of 1 mol dm^3 and gas at 100k kPa

Question 29

Transition element

Answer 29

A d-block element that forms an ion with an incomplete d sub shell

Question 30

Complex ion

Answer 30

A transition metal ion bonded to one or more ligands by coordinate bonds

Question 31

Ligand

Answer 31

A molecule or ion that can donate a pair of electrons to a transition metal ion to form a coordinate bonds

Question 32

Coordination number

Answer 32

The total number of coordinate bonds formed between a central metal ion and its ligands

Question 33

Stereoisomers

Answer 33

Species with the same structural formula but with a different arrangement of the atoms in space

Question 34

Ligand sub.

Answer 34

A reaction in which one ligand in a complex ion is replaced by another ligand

Question 35

Stability constant

Answer 35

The equilibrium constant for an equilibrium existing between a transition metal ion surrounded by water ligands and the complex formed when the same ion has undergone a ligand sub.