A2 Chemistry transition metals and enthalpy/entropy Flashcards
What is a D block element?
An element with its highest energy electron in the D-Subshell
What is a transition metal?
A transition metal forms at least one ion with a partially filled d-Subshell
What is a ligand?
A ligand is a chemical species with one or more lone pairs of electrons that bond to a metal ion to form a complex ion.
What is a dative covalent bond?
A dative covalent bond is a bond where two atoms share a pair of electrons donated by only one of the atoms in the bond
What is a ligand substitution reaction?
Where one ligand us replaced by another
What is stereoisomerism?
Stereoisomers are species with the same molecular formula but with different arrangements if atoms in space
What is the difference between cis and trains isomers?
A cis isomer has two of the same ligand 90° or next to each other
A trans isomer has the same ligand 180° from each other or on opposite ends of the molecule.
What is an optical isomer?
An optical isomers are non-superimposable mirror images of one another.
What is a Homogeneous catalyst?
A homogeneous catalyst is one which is in the same state as the reactants
What is a heterogeneous catalyst?
A heterogeneous catalyst is one which is in a different state to the reactants
What is enthalpy?
Enthalpy is the heat content stored in a chemical system.
What is the first law of thermodynamics?
Energy can not be created or destroyed, only transferred or transformed
What is activation energy?
Activation energy is the minimum energy required to start a reaction by breaking bonds.
What is enthalpy change if combustion?
Enthalpy change of combustion is the enthalpy change that occurs when one mole of a substance reacts completely with oxygen under standard conditions and with all reactants and products in their standard states
What is enthalpy change of formation?
Enthalpy change of formation is the enthalpy change that occurs when one mole of a substance is made from its constituent ions under standard conditions and with all reactants and products in their standard states
What is enthalpy of neutralisation?
Enthalpy change of neutralisation is the enthalpy change that occurs when an aqueous acid is neutralised by an aqueous base to form one mole of water under standard conditions.
State Hess’s Law
If a reaction can take more than one route, the overall enthalpy change will be the same for both routes provided the initial and final conditions and states are the same for both route
What are the standard conditions?
298°K, 101 kPa, 1moldm-3
What is bond enthalpy?
Bond enthalpy is the enthalpy change that takes place during homolytic fission of 1 mol of a given bond in the molecules of a gaseous species
What is entropy?
Entropy is the degree of disorder in a system.
What is the standard entropy of a substance?
The standard entropy of a substance is the entropy content of one mole of the substance under standard conditions.
Units: JK-1mol-1 joules per kelvin per mol
How do you work out the entropy change of a reaction?
Entropy change = the sum of the standard entropy of products - the sum of the standard entropy of reactants.
What is the standard entropy change of a reaction?
The entropy change that accompanies a reaction in the molar quantities expressed in a chemical equation with all reactants and products being in their standard states
What is the free energy change?
The free energy change /\G is the balance between enthalpy, entropy and temperature for a process.
/\G=/\H-T/\S
A process takes place spontaneously when G<0
