EEE Definitions Flashcards
Rate of reaction
The change in concentration of a reactant or product per unit time
Initial rate of reaction
The change in concentration of a reactant, or product per unit time at the start of the reaction when t=0
Order with respect to a reactant
The power to which the concentration is raised in the rate equation
Overall order of a reaction
The sum of the individual orders
The rate constant, k
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
Half life of a reactant
The time taken for the concentration of the reactant to halve
Reaction mechanism
A series of steps that together, make up the overall reaction
Rate-determining step
The slowest step in the reaction mechanism of a multi-step reaction
Dynamic equilibrium
The equilibrium that exists in a closed system when the rate of the forawrd reaction is equal to the rate of the reverse reaction
Homogeneous equilibrium
An equilibrium in which all the species making up the reactants and products are in the same physical state
Heterogeneous equilibrium
An equilibrium in which all the species making up the reactants and products are in the different physical state
Neutralisation
A reaction in which an acid and a base react together to form water and a salt
Acid-base pair
A pair of two species that transform into each other by gain or loss of a proton
Strong acid
An acid that completely dissociates in solution
Weak acid
An acid that partially dissociates in solution
Buffer solution
A mixture that minimizes pH changes on addition of small amounts of acid or base
Equivalence point
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
End point
The point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator
Standard enthalpy change of neutralisation
The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O under standard conditions
Lattice enthalpy
The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions
Standard enthalpy change of formation
The enthalpy change that take place when one mole of a compound is formed from its constituent elements under standard conditions
Enthalpy change of atomisation
Enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state
Standard enthalpy charge of solution
Enthalpy change that takes place when one mole of a compound is completely dissolves in water under standard condtions
Standard enthalpy change of hydration
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
Entropy
The quantitative measure of the degree of disorder in a system
Standard entropy change of reaction
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.
Free energy change
The balance between enthalpy, entropy and temperature for a process: ΔG = ΔH - TΔS
A process can take place spontaneously when ΔG < 0
Standard electrode potential of a half cell
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
Transition element
A d-block element that forms an ion with an incomplete d sub shell
Complex ion
A transition metal ion bonded to one or more ligands by coordinate bonds
Ligand
A molecule or ion that can donate a pair of electrons to a transition metal ion to form a coordinate bonds
Coordination number
The total number of coordinate bonds formed between a central metal ion and its ligands
Stereoisomers
Species with the same structural formula but with a different arrangement of the atoms in space
Ligand sub.
A reaction in which one ligand in a complex ion is replaced by another ligand
Stability constant
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.
