A2 Chemistry transition metals and enthalpy/entropy

Question 0

What is a D block element?

Answer 0

An element with its highest energy electron in the D-Subshell

Question 1

What is a transition metal?

Answer 1

A transition metal forms at least one ion with a partially filled d-Subshell

Question 2

What is a ligand?

Answer 2

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.

Question 3

What is a dative covalent bond?

Answer 3

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

Question 4

What is a ligand substitution reaction?

Answer 4

Where one ligand us replaced by another

Question 5

What is stereoisomerism?

Answer 5

Stereoisomers are species with the same molecular formula but with different arrangements if atoms in space

Question 6

What is the difference between cis and trains isomers?

Answer 6

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.

Question 7

What is an optical isomer?

Answer 7

An optical isomers are non-superimposable mirror images of one another.

Question 8

What is a Homogeneous catalyst?

Answer 8

A homogeneous catalyst is one which is in the same state as the reactants

Question 9

What is a heterogeneous catalyst?

Answer 9

A heterogeneous catalyst is one which is in a different state to the reactants

Question 10

What is enthalpy?

Answer 10

Enthalpy is the heat content stored in a chemical system.

Question 11

What is the first law of thermodynamics?

Answer 11

Energy can not be created or destroyed, only transferred or transformed

Question 12

What is activation energy?

Answer 12

Activation energy is the minimum energy required to start a reaction by breaking bonds.

Question 13

What is enthalpy change if combustion?

Answer 13

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

Question 14

What is enthalpy change of formation?

Answer 14

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

Question 15

What is enthalpy of neutralisation?

Answer 15

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.

Question 16

State Hess’s Law

Answer 16

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

Question 17

What are the standard conditions?

Answer 17

298°K, 101 kPa, 1moldm-3

Question 18

What is bond enthalpy?

Answer 18

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

Question 19

What is entropy?

Answer 19

Entropy is the degree of disorder in a system.

Question 20

What is the standard entropy of a substance?

Answer 20

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

Question 21

How do you work out the entropy change of a reaction?

Answer 21

Entropy change = the sum of the standard entropy of products - the sum of the standard entropy of reactants.

Question 22

What is the standard entropy change of a reaction?

Answer 22

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

Question 23

What is the free energy change?

Answer 23

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