Module 3 Flashcards
Second ionization energy
The energy required to remove one electron from each 1+ ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions
Successive ionization energy
A measure of the energy required to remove each electron in turn
Enthalpy change Delta H
The amount of heat released are absorbed by chemical eruption carried out. Constant pressure units = KJmol^-1
Standard enthalpy change of reaction Delta r H theta
The enthalpy change that accompanies a reaction in molar quantities expressed in a chemical equation, standard conditions, all reactants and products being in their standard states
Hess’ law
The enthalpy change of a reaction depends only on the initial and final states, and is independent of the route taken
Kc expression
See definition sheet A2 paper 1
Periodicity
Repeating trends in physical and chemical properties (1) Elements are arranged by increasing atomic (proton) number (1) in groups with similar chemical properties (1)
s/p/d elements
Example: An s-block element has its highest energy electron in an s subshell
First ionization energy
The energy required to remove one electron from each atom (1) in one mole of gaseous atoms to form one mole of gaseous 1+ ions (1)
Exothermic reaction
Reaction where heat energy is released to the surroundings Delta H is negative
Endothermic reaction
A reaction where heat energy is absorbed from the surroundings Delta H is positive
Average bond enthalpy Delta E H theta
The average enthalpy change for the breaking of one mole of bonds in gaseous molecules by homolytic fission
Standard conditions
Temperature equals 25° C , 298K
Pressure 1 atm, 100kPa
All solutions must have a concentration of 1.00 moldm^-3
Standard enthalpy change of neutralization Delta neutron H theta
The enthalpy change that accompanies the formation of one mole of H2O from neutralization under standard conditions
Standard enthalpy change of formation Delta f H theta
The enthalpy change where one mole of a compound is formed from its elements in their standard states under standard conditions
Standard enthalpy change of combustion delta c H theta
The enthalpy change for complete combustion of one mole of a substance under standard conditions, all reactants and products being in their standard states
Rate of reaction
The changing concentration of a reactant or a product per unit time
OR
Rate = concentration of reactant or product / time
Units = moldm^-3s^-1
Activation energy
The minimum energy required to start a reaction by breaking bonds
Heterogeneous catalysis
Catalysis of reaction in which the catalyst has a different physical state from the reactants
Homogenous catalysis
Catalysis of a reaction in which the catalyst and the reactants are in the same physical state
Dynamic equilibrium
Exists in a closed system (1) when the rate of the forward reaction is equal to the rate of the reverse reaction (1) and the concentrations of reactants and products do not change (1)
Le Chatelier’s principle
When a system in dynamic equilibrium is subjected to change, the equilibrium position will shift to minimize the change
