Definitions Flashcards
First Ionisation Energy
The energy required to convert one mole of gaseous atoms into gaseous ions with a a single positive charge
Second/Third Ionisation Energy
The energy required to convert one mole of gaseous ions with a single/double positive charge into gaseous ions with a double/triple positive charge
Standard Conditions
25°C(298K) and 1 atmosphere(100kPa)
Enthalpy of Reaction
Enthalpy change when the number of moles of substances reacts, as written in the equation
Standard enthalpy of combustion
The enthalpy change when one mole of a substance is completely burnt is oxygen under standard conditions
Standard enthalpy of formation
The enthalpy change when one mole of a compound is formed from its elements under standard conditions
Standard enthalpy of neutralisation
The enthalpy change when one mole of water is produced in a neutralisation reaction under standard conditions
Lattice enthalpy
The enthalpy change when one mole of an ionic compound is converted to gaseous ions.
Enthalpy of atomisation
The enthalpy change when one mole of gaseous atoms is formed from the element in its atomic state
First electron affinity
The enthalpy change when one mole of gaseous atoms is converted into gaseous ions with a single negative charge
Enthalpy of solution
The enthalpy change when one mole of a solute dissolves in water
Enthalpy of hydration
The enthalpy change when one mole of gaseous ions is converted to one mole of aqueous ions
Conservation of energy
Energy cannot be created or destroyed but it can be changed from one form to another
Hess’s Law
The enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same
Average bond enthalpy
The energy required to break one mole of a given bond averaged over many compounds
Bond enthalpy
The energy required to break one mole of a specific bond
Reaction rate
The change of the concentration (amount) of a reactant or product with respect to time
Order of reaction (with respect to a reactant)
The power to which the concentration of a reactant is raised in the rate equation
Order of reaction (overall)
The sum of the powers to which the concentration terms are raised in the rate equation
Rate constant
The proportionality constant which links the rate of the reaction to the concentrations in the rate equation
Rate determining step
The slowest step in the mechanism
Activation energy
The minimum amount of energy required for a reaction to occur
Homogenous
A reaction in which all the reactants and products are in the same physical state
Heterogenous
A reaction in which all the reactants and products are not in the same state
Feasible/Spontaneously
A reaction for which free energy is less than 0 (/_\G<0)
Entropy
A measure of disorder (randomness)
Dynamic Equilibrium
Rate of forward reaction is equal to the rate of backward reaction and the amount of each reactant/product remains constant.
Reversible
A reaction which goes in both the forward and backward directions.
Equilibrium
A reversible reaction in which the amount of each reactant/product remains constant.
Homogenous Equilibrium
A reaction in which all the reactants and products are in the same physical state.
Heterogenous Equilibrium
A reaction in which the reactants and products are in a different physical state.
Concentration.
Number of moles divided by volume.
Bronsted
Proton donor
Bronsted base
Proton acceptor
Kw
kw= (H+)(OH-)
Ka
Ka=[H+][A-]/[HA]
pH
pH= -log10[H+]
pKa
pKa= -log10Kw
Buffer Solution
A solution which resists change in pH on addition of small amounts of acid or alkali
Monobasic
Donates one proton per molecule
Asymmetrical Centre
An atom which has four different atoms or groups attached
Optical Isomers
Molecules which exist as non-superimposable mirror images
Optically active
As sample which rotates the plane of plane polarised light
Racemic Mixture
A 50:50 mixture of two optical isomers
Monoester
An ester which contains only one ester group
Transesterification
A reaction where the alkyl group of an ester is exchanged with the alkyl group of an alcohol
Biodiesel
A fuel, similar to diesel, which is made from vegetable sources. E.g. from the reaction of rape seed oil with methanol
