Key Definitions - EEE Flashcards
Rate of Reaction
Change in concentration of a reactant or product per unit time.
Initial rate of reaction
Change in concentration of reactant or product when t=0
Order of reaction
Power to which the concentration is raised in the rate equation
Overall order
Sum of the individual orders
Rate constant
links rate of reaction with the concentration of reactants raised to the power of their orders in the rate equation
Half life
The time taken for a reactant’s concentration to reduce by half
Reaction mechanism
series of steps which make up the overall reaction
Rate determining step
slowest step in a multi step reaction
Intermediate
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
Dynamic Equilibrium
exists in a closed system when the rate of reaction in forward direction is equal to rate of reaction in the reverse
Homogeneous Equilibrium
all reactants and products in the same physical state
Heterogeneous equilibrium
reactants and products in equilibrium in different physical states
Neutralisation
Chemical reaction when acid and base react to produce salt + H2O
Acid-Base pair
two species which are related to each other by gaining or loosing a proton
pH
-log[H+]
[H+]
10^-pH
Ka
([H+][A-})/[HA]
pKa
-logKa
Ka
10^-pKa
Ionic product of water
[H+][OH-] = 1x10^-14
ionic product - multiply the concentrations of ions in water
Buffer solution
mixture that minimises pH change on addition of small amounts of acid or base
Equivalence point
point in titration at which volume of one solution has reacted completely with volume of the second, matching stoichiometry
end point
equal concentrations of weak acid/conjugate base forms of the indicator. Colour is midway between colours for acid and base
Standard enthalpy change of neutralisation
energy change accompanying the neutralisation of aqueous acid with aqueous base to form one mole of H2O under standard conditions
Lattice enthalpy
Enthalpy change that accompanies the formation of one mole of ionic lattice from its gaseous ions under standard conditions
Hess’s Law
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
Standard enthalpy change of formation
enthalpy change accompanying formation of one mole of compound from its constituent elements in the standard states under standard conditions
enthalpy change of atomisation
enthalpy change accompanying the formation of one mole of gaseous atoms from the element in its standard state
First ionisation energy
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
Second ionisation energy
enthalpy change accompanying the removal of one electron from each ion in one mole of 1+ ions to form one mole of 2+ ions
First electron affinity
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
Second electron affinity
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
Standard enthalpy change of solution
enthalpy change that accompanies dissolving one mole of an ionic compound completely in water under standard conditions to form one mole of aqueous
ions.
Standard enthalpy change of hydration
enthalpy change accompanying dissolving one mole of gaseous atoms in water forming one mole of aqueous ions under standard conditions
Entropy
Quantitative measure of order or disorder in a system
Standard entropy change of reaction
entropy change that accompanies reaction in molar quantities expressed in equation under standard conditions in standard states
Free energy change
Balance between enthalpy, entropy and temperature for a process:G=H-TS
T is measured in K, and reactions are spontaneous if G
Oxidation
Loss of electrons/increase in oxidation number
Reduction
Gain of electrons, decrease in oxidation number
Standard electrode potential
EMF that exists between a given half cell and standard hydrogen electrode under standard conditions of 1 molem-3, 1 atm and 298k
Transition element
D-block element that can form one or more ions with an incomplete d sub-shell
Complex ion
Transition metal ion covalently bonded to one or more ligands
Ligand
Species that can donate a lone pair of electrons to a central transition metal ion to form a new co-ordinate bond
CO-ordination number
The number of co-ordinate bonds between a central transition metal ion and its linands
Stereoisomerism
species with same structural formula but a different arrangement in space
Ligand substitution
A reaction in which one ligand replaces another in a complex
Stability constant, KStab
equilibrium constant for transition metal surrounded by water ligands compared to having undergone total ligand substitution
